well you do not upgrade your http/1.1 connection. http/2 works by using ALPN on TLS connections, that actually try to get the right protocol. yeah there is h2c,

well you do not upgrade your http/1.1 connection. http/2 works by using ALPN on TLS connections, that actually try to get the right protocol. yeah there is h2c, which does upgrade the connection, but that only works in backend scenarios without tls.