> Doubt it. I suspect that browsers have some sort of happy eyeballs algorithm for determining whether to use http/3 specifically because some networks don't ha

> Doubt it. I suspect that browsers have some sort of happy eyeballs algorithm for determining whether to use http/3 specifically because some networks don't handle it well. On day zero? Sure. But then good networks will slowly enable UDP/443 anyway, and have good cover because it's The Web, and eventually it'll be enabled on more than 90% of networks. Then a few non-browser applications that use QUIC/HTTPS will decide that 90% is good enough and start to not support TCP anymore, causing trouble for the holdouts and getting it enabled on 95% of networks. Then even more applications will do that. At some point the browsers can put up a warning when fallback happens, telling the user that their network is degrading performance. Eventually the number of networks that don't support it is small enough that nobody supports fallback anymore. > How so? how is TCP 80/443 and UDP 80/443 harder to traffic shape than TCP 80/443 alone? They can't mess with window sizes and such because they're inside the encrypted payload.