"Quote from: tomdh76 on September 18, 2025, 03:16:53 PMThanks for this post. I had ISC dhcp working fine with Ipv6 but I saw that it was advised to go to Dnsmasq. After a week bad DNS (some sites like this forum even got 'timed out') I switched back to the normal Router advertisements and everything worked instantly.
Necrobumping this thread as I stumbled on nearly the exact same issue. For me DNS didn't seem to be the issue as the behavior was the same regardless of if using local DNS resolution or a public resolver. The issue I found was TLS connections not establishing as expected for IPv6. Moving back to kea + router advertisements is my immediate fix, but getting to the root of why DNSMASQ didn't play nice would be great.
I'll also crosspost my Reddit post for anyone in the future who may stumble on this: https://www.reddit.com/r/opnsense/comments/1r9uxs0/odd_ipv6_traffic_behavior_dnsmasq/
Affects me on opnsense 26.1.2_5 on top of proxmox
