I did figure out that ufw was not allowing udp/443. So it turns out that wasn't working for any website on that install.
Ah yep, the fact that allow 443 implies allow tcp/443 and you need to explicitly allow udp/443 is yet another "quirky" thing (to be polite...)
But even after allowing udp/443, it is still not switching. If I enter the URL into https://http3check.net/ it does say that http3 works.
Yup that sounds about right
Hmm. The web server is on the local gigabit LAN with the client. Would that give TCP a significant enough boost that it could beat UDP?
Hard to say; in our case it seemed more random than actually driven by anything remotely close to clear. I'm merely quoting official word on it, but have yet to try and dig the actual source code for how it happens. The only platform I know gets reliable QUIC enabling is CF, so maybe someone from their side could chime in if they ever see this.
I have chrome, not chromium. Substituting /opt/google/chrome/chrome for chromium and running it with those options, it DOES do http/3. The lightning bolt is orange instead of blue.
Then yep, you're in the same boat as we were. It switched for no reason one day. Even trying HTTPS/SVCB DNS records did nothing for us until it "magically" decided to use H3.
Tristan
