IPv6 from Android devices still broken

[reinob]

I'm not sure if the issue(s) reported here are the same or related to the issue I had, but just in case: I bought a Motorola Edge 70 (in case the model matters), which runs Android 16. I quickly noticed that after a few minutes (sometimes longer) IPv6 connectivity stopped working (like visiting ipv6-test.com, or ping6 www.google.com from termux). This would work after rebooting, or switching airplane mode off/on, or turning WLAN off for a while and then back on.

I'm still on Opnsense 25.7 (need to find the time to upgrade w/o causing disturbance at home..), and was using the standard RA daemon (and DNSMASQ for DHCP). I tried all sorts of combinations of RA lifetimes, etc. but couldn't get it to work reliably. I then switched to dnsmasq (defined an IPv6 range and enabled "ra-statless", tried also with "ra-names" and with "slaac"). and it still didn't work reliably.

Out of desperation I then enabled ra-advrouter (and only that mode), and suddenly (OK, I restarted the phone yet again, just to make sure I started with a clean state) IPv6 has been working reliably for about 24h, including short and long sleep/doze periods.

I'm by no means an IPv6 expert, and I still have to read RFC 3775 sections 7.2 and 7.3, but maybe this can serve as a workaround to other users of Android 16 affected by this, and (maybe) some expert might be able to explain why this works.

Thanks.