I’m testing out DoH on the new Slate AX I got for Christmas and using the IPv6 host at my preferred provider seems to reliably result in slow name lookup and occasional timeouts. I am not using Adguard Home, rather I’ve set this up in the “DNS” section of Network settings in the GLi firmware. Edit: I’m also using OpenVPN.
When I enabled DoH I added two entries from the built-in server list, namely quad9-doh-ip4-port443-filter-pri and quad9-doh-ip6-port443-filter-pri
After a while I noticed that all name lookups were laggy and sometimes failing. Quad9 has always performed well for me when I use their normal DNS service on IPv4, and they have a POP near where my VPN terminates.
I eventually found that removing the IPv6 server from the list in the GLi DNS settings eliminates the problem. Not sure if this is a bug or not, but I figured I’d make a post either way - if it’s a bug then I’ve reported it, if it’s undocumented behavior then the post will exist for people searching on the forum.
Happy 2023 everyone.