siegfried36
Oct 26, 2021, updated at Dec 20, 2021 (UTC)
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IPv6: Server cannnot ping gateway but gets IP

QuestionLinux NetworkLinux
I have three servers which should now also get IPv6 connectivity besides the IPv4.
Servers:
1. Pi4 (Raspberry Pi OS)
2. Nextcloud (Debian 10; Nextcloud as snap)
3. Mailserver (Debian 10; mailcow as docker, which also uses IPv6)

They are directly connected to the firewall (up to date pfSense) and reside in their own subnet/VLAN. My plan is to use DCHPv6 so that I can give them a fixed IP, from where I can use DNS and firewall rules.
From my ISP I got /56 subnet via prefix daligation and in my network every subnet gets a /64 chunk of that.
The config of the DHCP-server is for all servers the same and is as follows:
RA-Advertisment -> managed
Range -> from ::d:000 to ::d:ffff

Server 1. - Pi4:
Gets the wanted v6 IP from the firewall (static entry) -> xxxxxxx::d:1. Can ping the firewall and the firewall can ping the host.
$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether dc:a6:32:ba:a6:40 brd ff:ff:ff:ff:ff:ff
    inet 192.168.7.2/24 brd 192.168.7.255 scope global dynamic noprefixroute eth0
       valid_lft 5564sec preferred_lft 4664sec
    inet6 2a02:8106:26:c207::d:1/128 scope global dynamic noprefixroute 
       valid_lft 6268sec preferred_lft 3568sec
    inet6 2a02:8106:26:c207:4f5b:7339:9f6f:6b9e/64 scope global dynamic mngtmpaddr noprefixroute 
       valid_lft 86394sec preferred_lft 14394sec
    inet6 fe80::3958:1364:8c6e:21ca/64 scope link 
       valid_lft forever preferred_lft forever

$ ip r
default via 192.168.7.1 dev eth0 proto dhcp src 192.168.7.2 metric 202 
192.168.7.0/24 dev eth0 proto dhcp scope link src 192.168.7.2 metric 202 

$ cat nano /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)

# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf' 

# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

Server 2. - Nextcloud:
Gets not the wanted v6 IP from the firewall (static entry) -> xxxxxxx::d:1. I don't know why, but it gets one out of the DHCP range -> ::d:3066 without the static entry. Can ping the firewall and the firewall can ping the host. The server is reachable as wanted.
$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether d0:50:99:76:7d:6b brd ff:ff:ff:ff:ff:ff
    inet 192.168.5.2/24 brd 192.168.5.255 scope global dynamic eth0
       valid_lft 6796sec preferred_lft 6796sec
    inet6 2a02:8106:26:c205::d:3066/128 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::d250:99ff:fe76:7d6b/64 scope link 
       valid_lft forever preferred_lft forever
3: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:44:56:66:5e brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:44ff:fe56:665e/64 scope link 
       valid_lft forever preferred_lft forever
5: veth16f1c55@if4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
    link/ether 76:f8:c2:66:64:c2 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet6 fe80::74f8:c2ff:fe66:64c2/64 scope link 
       valid_lft forever preferred_lft forever
7: veth624ab49@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
    link/ether f2:88:68:74:9b:a7 brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet6 fe80::f088:68ff:fe74:9ba7/64 scope link 
       valid_lft forever preferred_lft forever

$ ip r
default via 192.168.5.1 dev eth0 
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 
192.168.5.0/24 dev eth0 proto kernel scope link src 192.168.5.2 

$ cat /etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet dhcp
# This is an autoconfigured IPv6 interface
iface eth0 inet6 dhcp

Server 3. - Mailcow:
Gets not the wanted v6 IP from the firewall (static entry) -> xxxxxxx::d:1. I don't know why, but it gets one out of the DHCP range -> 2a02:8106:26:c206::d:1fd7 without the static entry. Can't ping the firewall
$ ping 2a02:8106:26:c206:ec4:7aff:feac:791a 
connect: network is not reachable

and the firewall can't ping the host. The server is not reachable at all.

$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp0s25: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0b:ab:9c:b3:40 brd ff:ff:ff:ff:ff:ff
    inet 192.168.6.2/24 brd 192.168.6.255 scope global dynamic enp0s25
       valid_lft 6115sec preferred_lft 6115sec
    inet6 2a02:8106:26:c206::d:1fd7/128 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::20b:abff:fe9c:b340/64 scope link 
       valid_lft forever preferred_lft forever
3: ens36: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 00:0b:ab:9c:b3:41 brd ff:ff:ff:ff:ff:ff
4: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:86:52:78:26 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:86ff:fe52:7826/64 scope link 
       valid_lft forever preferred_lft forever
    inet6 fe80::1/64 scope link 
       valid_lft forever preferred_lft forever
5: br-mailcow: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:98:71:e4:00 brd ff:ff:ff:ff:ff:ff
    inet 172.22.1.1/24 brd 172.22.1.255 scope global br-mailcow
       valid_lft forever preferred_lft forever
    inet6 fe80::42:98ff:fe71:e400/64 scope link 
       valid_lft forever preferred_lft forever
    inet6 fe80::1/64 scope link 
       valid_lft forever preferred_lft forever
7: veth9d1c8e9@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 92:69:ae:5f:16:94 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet6 fe80::9069:aeff:fe5f:1694/64 scope link 
       valid_lft forever preferred_lft forever
9: veth8c82697@if8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
    link/ether ea:dd:2f:06:a8:ac brd ff:ff:ff:ff:ff:ff link-netnsid 3
    inet6 fe80::e8dd:2fff:fe06:a8ac/64 scope link 
       valid_lft forever preferred_lft forever
11: vethe900989@if10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether ee:45:28:e8:f8:65 brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet6 fe80::ec45:28ff:fee8:f865/64 scope link 
       valid_lft forever preferred_lft forever
13: vethfca3d8a@if12: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 72:0e:57:52:f6:8c brd ff:ff:ff:ff:ff:ff link-netnsid 2
    inet6 fe80::700e:57ff:fe52:f68c/64 scope link 
       valid_lft forever preferred_lft forever
15: veth047f50f@if14: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 32:d4:40:15:0c:7f brd ff:ff:ff:ff:ff:ff link-netnsid 4
    inet6 fe80::30d4:40ff:fe15:c7f/64 scope link 
       valid_lft forever preferred_lft forever
17: vethf6245fe@if16: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 26:53:8b:26:c9:38 brd ff:ff:ff:ff:ff:ff link-netnsid 7
    inet6 fe80::2453:8bff:fe26:c938/64 scope link 
       valid_lft forever preferred_lft forever
19: veth21a6fa3@if18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 5a:a7:a7:e2:86:5b brd ff:ff:ff:ff:ff:ff link-netnsid 6
    inet6 fe80::58a7:a7ff:fee2:865b/64 scope link 
       valid_lft forever preferred_lft forever
21: vethd2d1e06@if20: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 8e:79:e5:0e:a6:f1 brd ff:ff:ff:ff:ff:ff link-netnsid 10
    inet6 fe80::8c79:e5ff:fe0e:a6f1/64 scope link 
       valid_lft forever preferred_lft forever
23: vethc10d2bc@if22: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 76:99:da:1d:cd:0e brd ff:ff:ff:ff:ff:ff link-netnsid 9
    inet6 fe80::7499:daff:fe1d:cd0e/64 scope link 
       valid_lft forever preferred_lft forever
25: veth201bcfc@if24: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 46:d4:93:82:4b:6b brd ff:ff:ff:ff:ff:ff link-netnsid 8
    inet6 fe80::44d4:93ff:fe82:4b6b/64 scope link 
       valid_lft forever preferred_lft forever
27: vethad8e436@if26: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether da:24:e6:37:3a:8c brd ff:ff:ff:ff:ff:ff link-netnsid 5
    inet6 fe80::d824:e6ff:fe37:3a8c/64 scope link 
       valid_lft forever preferred_lft forever
29: vethbaf78e4@if28: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 9e:01:7b:70:9a:31 brd ff:ff:ff:ff:ff:ff link-netnsid 15
    inet6 fe80::9c01:7bff:fe70:9a31/64 scope link 
       valid_lft forever preferred_lft forever
31: veth7eada94@if30: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 2a:bd:24:d6:e9:8a brd ff:ff:ff:ff:ff:ff link-netnsid 13
    inet6 fe80::28bd:24ff:fed6:e98a/64 scope link 
       valid_lft forever preferred_lft forever
33: vethd1e707c@if32: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 7a:71:37:59:58:43 brd ff:ff:ff:ff:ff:ff link-netnsid 16
    inet6 fe80::7871:37ff:fe59:5843/64 scope link 
       valid_lft forever preferred_lft forever
35: veth6d78c43@if34: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 42:f1:b5:53:f5:5c brd ff:ff:ff:ff:ff:ff link-netnsid 14
    inet6 fe80::40f1:b5ff:fe53:f55c/64 scope link 
       valid_lft forever preferred_lft forever
37: vethd1a9600@if36: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 52:15:e7:eb:3e:ea brd ff:ff:ff:ff:ff:ff link-netnsid 11
    inet6 fe80::5015:e7ff:feeb:3eea/64 scope link 
       valid_lft forever preferred_lft forever
39: veth621f244@if38: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 1e:af:a7:76:8e:c8 brd ff:ff:ff:ff:ff:ff link-netnsid 12
    inet6 fe80::1caf:a7ff:fe76:8ec8/64 scope link 
       valid_lft forever preferred_lft forever
41: veth4284cea@if40: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-mailcow state UP group default 
    link/ether 32:ee:4d:9c:fb:6c brd ff:ff:ff:ff:ff:ff link-netnsid 17
    inet6 fe80::30ee:4dff:fe9c:fb6c/64 scope link 
       valid_lft forever preferred_lft forever

$ ip r
default via 192.168.6.1 dev enp0s25 
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 
172.22.1.0/24 dev br-mailcow proto kernel scope link src 172.22.1.1 
192.168.6.0/24 dev enp0s25 proto kernel scope link src 192.168.6.2 

$ cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug enp0s25
iface enp0s25 inet dhcp
# This is an autoconfigured IPv6 interface


Why is server 3 not reachable, as it has the same configurations as server 2? Shouldn't an IPv6 address also be available in the routes?

best regards
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Content-Key: 1432568295

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Printed on: April 18, 2024 at 21:04 o'clock

5 Comments
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Member: Siegfried36
Siegfried36 Oct 26, 2021 at 12:14:53 (UTC)
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This is the outpout of

watch ip -6 route

pfsense3
pfsense4

The first and second picture is the fully reachable PI and the Nextcloud host.

pfsense5

The the third is the problematic one. It seems that it don't get/has the default gateway like in the other pictures:default via fe80::ec4:7aff:feac:791a ...(it is the right gateway address)
Member: Siegfried36
Siegfried36 Oct 26, 2021 updated at 12:17:03 (UTC)
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Now it works. Now the host (server 3) is a reachable but only with a static entry in the network/interfaces with ->
  1. nano /etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug enp0s25
iface enp0s25 inet dhcp
# This is an autoconfigured IPv6 interface
#iface enp0s25 inet6 dhcp
iface enp0s25 inet6 static
	address 2a02:8106:26:c206::d:1
	netmask 64
	gateway 2a02:8106:26:c206:ec4:7aff:feac:791a

But whhyyyyyyyy???
Member: aqui
aqui Oct 26, 2021 updated at 14:00:23 (UTC)
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The server is not reachable at all.
As you can see all docker interfaces do not have any public v6 address. They have only v4 addresses and in terms of v6 only v6 link local addresses which cannot provide Internet connectivity of course.
So something is wrong there with ICMPv6 (SLAAC) or DHCPv6 providing the docker interface/hosts with valid v6 addresses.
Either ICMPv6 oder DHCPv6 or both is blocked there. Run a tcpdump trace to check.
Member: Siegfried36
Siegfried36 Oct 26, 2021 updated at 14:24:18 (UTC)
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Quote from @aqui:

The server is not reachable at all.
As you can see all docker interfaces do not have any public v6 address. They have only v4 addresses and in terms of v6 only v6 link local addresses which cannot provide Internet connectivity of course.
So something is wrong there with ICMPv6 (SLAAC) or DHCPv6 providing the docker interface/hosts with valid v6 addresses.


I think the docker are are fine, because mailcow runs fully under v6 and runs under IPv4 fine. The problem now is that the interface enp0s25 won't get the v6 gateway address.

Either ICMPv6 oder DHCPv6 or both is blocked there. Run a tcpdump trace to check.
Ok, I will check that.
Member: Siegfried36
Siegfried36 Oct 26, 2021 updated at 18:07:18 (UTC)
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I ran tcpdump out of the blue with:
$ sudo tcpdump -i enp0s25 -vvv -nn ip6

It gave me the following output:
tcpdump: listening on enp0s25, link-type EN10MB (Ethernet), capture size 262144 bytes
19:10:21.067575 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 136) fe80::ec4:7aff:feac:791a > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 136
	hop limit 64, Flags [managed, other stateful], pref medium, router lifetime 60s, reachable time 0ms, retrans timer 0ms
	  prefix info option (3), length 32 (4): 2a02:8106:26:c206::/64, Flags [onlink], valid time 86400s, pref. time 14400s
	    0x0000:  4080 0001 5180 0000 3840 0000 0000 2a02
	    0x0010:  8106 0026 c206 0000 0000 0000 0000
	  route info option (24), length 24 (3):  ::/0, pref=medium, lifetime=60s
	    0x0000:  0000 0000 003c 0000 0000 0000 0000 0000
	    0x0010:  0000 0000 0000
	  rdnss option (25), length 24 (3):  lifetime 60s, addr: 2a02:8106:26:c206:ec4:7aff:feac:791a
	    0x0000:  0000 0000 003c 2a02 8106 0026 c206 0ec4
	    0x0010:  7aff feac 791a
	  dnssl option (31), length 24 (3):  lifetime 20s, domain(s): localdomain.
	    0x0000:  0000 0000 0014 0b6c 6f63 616c 646f 6d61
	    0x0010:  696e 0000 0000
	  mtu option (5), length 8 (1):  1500
	    0x0000:  0000 0000 05dc
	  source link-address option (1), length 8 (1): 0c:c4:7a:ac:79:1a
	    0x0000:  0cc4 7aac 791a
19:10:26.381445 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 136) fe80::ec4:7aff:feac:791a > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 136
	hop limit 64, Flags [managed, other stateful], pref medium, router lifetime 60s, reachable time 0ms, retrans timer 0ms
	  prefix info option (3), length 32 (4): 2a02:8106:26:c206::/64, Flags [onlink], valid time 86400s, pref. time 14400s
	    0x0000:  4080 0001 5180 0000 3840 0000 0000 2a02
	    0x0010:  8106 0026 c206 0000 0000 0000 0000
	  route info option (24), length 24 (3):  ::/0, pref=medium, lifetime=60s
	    0x0000:  0000 0000 003c 0000 0000 0000 0000 0000
	    0x0010:  0000 0000 0000
	  rdnss option (25), length 24 (3):  lifetime 60s, addr: 2a02:8106:26:c206:ec4:7aff:feac:791a
	    0x0000:  0000 0000 003c 2a02 8106 0026 c206 0ec4
	    0x0010:  7aff feac 791a
	  dnssl option (31), length 24 (3):  lifetime 20s, domain(s): localdomain.
	    0x0000:  0000 0000 0014 0b6c 6f63 616c 646f 6d61
	    0x0010:  696e 0000 0000
	  mtu option (5), length 8 (1):  1500
	    0x0000:  0000 0000 05dc
	  source link-address option (1), length 8 (1): 0c:c4:7a:ac:79:1a
	    0x0000:  0cc4 7aac 791a
19:10:39.131743 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 136) fe80::ec4:7aff:feac:791a > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 136
	hop limit 64, Flags [managed, other stateful], pref medium, router lifetime 60s, reachable time 0ms, retrans timer 0ms
	  prefix info option (3), length 32 (4): 2a02:8106:26:c206::/64, Flags [onlink], valid time 86400s, pref. time 14400s
	    0x0000:  4080 0001 5180 0000 3840 0000 0000 2a02
	    0x0010:  8106 0026 c206 0000 0000 0000 0000
	  route info option (24), length 24 (3):  ::/0, pref=medium, lifetime=60s
	    0x0000:  0000 0000 003c 0000 0000 0000 0000 0000
	    0x0010:  0000 0000 0000
	  rdnss option (25), length 24 (3):  lifetime 60s, addr: 2a02:8106:26:c206:ec4:7aff:feac:791a
	    0x0000:  0000 0000 003c 2a02 8106 0026 c206 0ec4
	    0x0010:  7aff feac 791a
	  dnssl option (31), length 24 (3):  lifetime 20s, domain(s): localdomain.
	    0x0000:  0000 0000 0014 0b6c 6f63 616c 646f 6d61
	    0x0010:  696e 0000 0000
	  mtu option (5), length 8 (1):  1500
	    0x0000:  0000 0000 05dc
	  source link-address option (1), length 8 (1): 0c:c4:7a:ac:79:1a
	    0x0000:  0cc4 7aac 791a
19:10:51.563041 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 136) fe80::ec4:7aff:feac:791a > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 136
	hop limit 64, Flags [managed, other stateful], pref medium, router lifetime 60s, reachable time 0ms, retrans timer 0ms
	  prefix info option (3), length 32 (4): 2a02:8106:26:c206::/64, Flags [onlink], valid time 86400s, pref. time 14400s
	    0x0000:  4080 0001 5180 0000 3840 0000 0000 2a02
	    0x0010:  8106 0026 c206 0000 0000 0000 0000
	  route info option (24), length 24 (3):  ::/0, pref=medium, lifetime=60s
	    0x0000:  0000 0000 003c 0000 0000 0000 0000 0000
	    0x0010:  0000 0000 0000
	  rdnss option (25), length 24 (3):  lifetime 60s, addr: 2a02:8106:26:c206:ec4:7aff:feac:791a
	    0x0000:  0000 0000 003c 2a02 8106 0026 c206 0ec4
	    0x0010:  7aff feac 791a
	  dnssl option (31), length 24 (3):  lifetime 20s, domain(s): localdomain.
	    0x0000:  0000 0000 0014 0b6c 6f63 616c 646f 6d61
	    0x0010:  696e 0000 0000
	  mtu option (5), length 8 (1):  1500
	    0x0000:  0000 0000 05dc
	  source link-address option (1), length 8 (1): 0c:c4:7a:ac:79:1a
	    0x0000:  0cc4 7aac 791a
19:11:07.717653 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 136) fe80::ec4:7aff:feac:791a > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 136
	hop limit 64, Flags [managed, other stateful], pref medium, router lifetime 60s, reachable time 0ms, retrans timer 0ms
	  prefix info option (3), length 32 (4): 2a02:8106:26:c206::/64, Flags [onlink], valid time 86400s, pref. time 14400s
	    0x0000:  4080 0001 5180 0000 3840 0000 0000 2a02
	    0x0010:  8106 0026 c206 0000 0000 0000 0000
	  route info option (24), length 24 (3):  ::/0, pref=medium, lifetime=60s
	    0x0000:  0000 0000 003c 0000 0000 0000 0000 0000
	    0x0010:  0000 0000 0000
	  rdnss option (25), length 24 (3):  lifetime 60s, addr: 2a02:8106:26:c206:ec4:7aff:feac:791a
	    0x0000:  0000 0000 003c 2a02 8106 0026 c206 0ec4
	    0x0010:  7aff feac 791a
	  dnssl option (31), length 24 (3):  lifetime 20s, domain(s): localdomain.
	    0x0000:  0000 0000 0014 0b6c 6f63 616c 646f 6d61
	    0x0010:  696e 0000 0000
	  mtu option (5), length 8 (1):  1500
	    0x0000:  0000 0000 05dc
	  source link-address option (1), length 8 (1): 0c:c4:7a:ac:79:1a
	    0x0000:  0cc4 7aac 791a
19:11:16.550619 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 136) fe80::ec4:7aff:feac:791a > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 136
	hop limit 64, Flags [managed, other stateful], pref medium, router lifetime 60s, reachable time 0ms, retrans timer 0ms
	  prefix info option (3), length 32 (4): 2a02:8106:26:c206::/64, Flags [onlink], valid time 86400s, pref. time 14400s
	    0x0000:  4080 0001 5180 0000 3840 0000 0000 2a02
	    0x0010:  8106 0026 c206 0000 0000 0000 0000
	  route info option (24), length 24 (3):  ::/0, pref=medium, lifetime=60s
	    0x0000:  0000 0000 003c 0000 0000 0000 0000 0000
	    0x0010:  0000 0000 0000
	  rdnss option (25), length 24 (3):  lifetime 60s, addr: 2a02:8106:26:c206:ec4:7aff:feac:791a
	    0x0000:  0000 0000 003c 2a02 8106 0026 c206 0ec4
	    0x0010:  7aff feac 791a
	  dnssl option (31), length 24 (3):  lifetime 20s, domain(s): localdomain.
	    0x0000:  0000 0000 0014 0b6c 6f63 616c 646f 6d61
	    0x0010:  696e 0000 0000
	  mtu option (5), length 8 (1):  1500
	    0x0000:  0000 0000 05dc
	  source link-address option (1), length 8 (1): 0c:c4:7a:ac:79:1a
	    0x0000:  0cc4 7aac 791a

The router advertisement is nearly the same compared to the fully reachable host, so the problem must be the host, I guess.
QuestionLinux NetworkLinux
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