RADVD stops announcing IPv6 prefix after a while

[jchm]

Hi, I'm on OPNsense 24.1.5_3-amd64.

I am losing IPv6 internet connectivity after 5 or 6 minutes (sometimes less).
Only Internet connectivity because if I ping other IPv6 GUA address inside my network it works as shown in the images below

Left:  ping ipv6.google.com (suddenly stops after a while) - Right: ping a GUA address on my network (never stops).


I've realized that this happens because radvd stops announcing the prefix and does not reply to solicit messages any more. Restarting radvd from the web GUI fixes this, and then happens again after some minutes later.

I've also thought maybe it's a matter of my ISP, but testing the connection using OpenWRT it's pretty stable and there's no glitch. So, I think it's some configuration of OPNSense.

My setup is:
 - LAN IPv6 Configuration Type: Track Interface, Allow manual adjustment of DHCPv6 and Router Advertisements.
 - WAN PPPoE, DHCPv6, Request only an IPv6 prefix, Prefix delegation size: 56, send IPv6 prefix hint: 0, Use IPv4 connectivity.
 - Router Advertisements: Unmanaged, Minimum Interval 200, Maximum Interval: 600

Any clue, what is happening?

Thanks in advance