I deleted my network config file and rebooted, and set everything again because ipv6 gateway would show missing. the problem resolved, but has come back again after a reboot:

Automatic assignment assigns the correct gateway address. It works fine for br2, another bonded network that I have. Started facing this issue after upgrade to 7.1.4

param-diagnostics-20250710-1721.zip

Looks like only one of the network between br0 and br2 can have a static ipv6. With ipv6 disabled in br2, br0 ipv6 config worked as intended.

if you use an ULA (universal local address) like FDxx... , no Addresses on the internet can be reached. Thats why there is no default gateway.

Therefor your DNS assignmenet (2606...) will not work.

Also, the gateway will usually be detected automatically (it annouces itself) but only on the cable where it is located. The FE80... address is "cable only" ("only THIS card!"), ("FDxx" is "lan only" including all cards).

If you attach many brX to the same cable, the outcome is random and not really predictable. Avoid this at all costs.

So BR0 and BR2 should not be connected to each others by any means.

It is also normal to have only ONE default gateway (many may exist but then with different priorities, else routing is in trouble)

Edited July 11, 2025Jul 11 by MAM59