Wire-protocol mode of the native transport. The transport owns the choice
and the fallback; the library only passes the caller's intent.
auto — do what the app does for the profile. For ios.http: try HTTP/3
over QUIC with a short bounded attempt and fall back to HTTP/2 over TCP
silently when it does not get through, decided per connection. For the
Android profile: HTTP/2 only.
http2 — HTTP/2 over TCP only, for any profile.
http3 — HTTP/3 over QUIC only, an error when it cannot connect; for the
Android profile it is the caller's opt-in to the app's QUIC path (since
transport 0.9.21), never the default.
Wire-protocol mode of the native transport. The transport owns the choice and the fallback; the library only passes the caller's intent.
auto— do what the app does for the profile. Forios.http: try HTTP/3 over QUIC with a short bounded attempt and fall back to HTTP/2 over TCP silently when it does not get through, decided per connection. For the Android profile: HTTP/2 only.http2— HTTP/2 over TCP only, for any profile.http3— HTTP/3 over QUIC only, an error when it cannot connect; for the Android profile it is the caller's opt-in to the app's QUIC path (since transport 0.9.21), never the default.