How to configure Kestrel to serve HTTP/3 in ASP.NET Core 11
A complete guide to enabling HTTP/3 on Kestrel in ASP.NET Core 11: the HttpProtocols.Http1AndHttp2AndHttp3 endpoint config, MsQuic platform requirements on Windows, Linux, and macOS, why the first request is never HTTP/3, how to verify with HttpClient and middleware, QuicTransportOptions tuning, and the firewall and proxy gotchas that make it silently fall back.