Not my ISP (Init7 FTW!), but my router (Mikrotik) is notoriously infamous for being a total crap at IPv6 (see for example https://michael.stapelberg.ch/posts/2021-05-28-configured-an...)
In my particular case there seems to be an odd bug / misconfiguration from my side that makes the router / clients from time to time loose the IPv6 routing. The fallback is... a connection hanging forever. The only fix? Reconnecting to the Wi-Fi to get refresh the DHCP lease.
I debugged it for waay too long, and at this point I'm 80% convinced it's a Mikrotik bug of some sort.
I've also had no issues with IPv6 on my Mikrotik router (RB5009) - I did have to set the MTU to 1280 because of some poor IPv6 implementations elsewhere for a stable connection, though.
Another Init7 customer here (awesome ISP); I can recommend using OPNsense/pfSense or OpenWrt on alternative hardware
P.S. I have a R86S-G4 to sell, which is pretty good for running any of these at 10Gb speeds - feel free to DM me if interested (or let me know if I should DM you)
Same here. Init7 customer running OpnSense for many smooth/stable years already.
Are you running the long-term (6.x) branch? RouterOS 7.x (stable) is much better at IPv6 as far as I know.
I'm using 7.19.2 at the moment, still has this bug (or again, could be a misconfiguration from my side, but it looks veeery odd)
No IPv6 issues with a Mikrotik router here (CCR1009).