OPNsense Forum

English Forums => General Discussion => Topic started by: ciaduck on May 26, 2026, 12:03:11 AM

Title: Multi-WAN IPv6 Prefix Deprecation Problem
Post by: ciaduck on May 26, 2026, 12:03:11 AM
I'm having some issues with multi-wan failover using IPv6.

WAN is DHCPv6

WAN2 is set to SLAAC via LTE Modem, I'm not as concerned that this doesn't seem to work for ipv6 at the moment. I've been able to get things to work with NPT, but I think I will assign dedicated NAT addresses in the future, because NPT needs to also be updated every time the WAN prefix changes.

LAN is set to "Track Interface"

I'm using radv "Router Advertisements" in the services.
It set to "Assisted" with "Automatic" source address.
I've not set any advanced options, everything is default.

I tested my failover by unplugging the cable from my cable modem. When service was restored, the gateway monitoring functioned, and fail to LTE was fine. Once I plugged it back in, I noticed a lot of delay trying to get to test-ipv6.com

I had the same issue on my phone. I cycled the wifi connection on and off and it solved it.

I can see from a windows client that I still have the old prefix/address.

What can I do to solve this issue? I'd like to have clients properly deprecate/abandon an old address when the WAN flaps.

Here is an example output from ifconfig. The c881 is the new address, and the c800 is the old one.
Ethernet adapter Ethernet:

   Connection-specific DNS Suffix  . : home.arpa
   IPv6 Address. . . . . . . . . . . : 2601:281:c881:fb80:1a7a:5927:4cd4:e21b
   IPv6 Address. . . . . . . . . . . : 2601:281:c800:3910:3e2f:a436:d203:d072
   Temporary IPv6 Address. . . . . . : 2601:281:c800:3910:a512:d226:8873:46cb
   Temporary IPv6 Address. . . . . . : 2601:281:c881:fb80:a857:a7c4:21fe:3929
   Link-local IPv6 Address . . . . . : fe80::d1fd:217e:6ec2:961%25
   IPv4 Address. . . . . . . . . . . : 192.168.1.161
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.1.1

Should I set radv lifetimes to something more aggressive than the defaults?