master-server/deps/curl/docs/cmdline-opts/no-alpn.md

c	SPDX-License-Identifier	Long	Tags	Protocols	Added	Requires	Help	Category	Multi	See-also	Example
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.	curl	no-alpn	HTTP/2	HTTPS	7.36.0	TLS	Disable the ALPN TLS extension	tls http	boolean	no-npn http2	--no-alpn $URL

--no-alpn

Disable the ALPN TLS extension. ALPN is enabled by default if libcurl was built with an SSL library that supports ALPN. ALPN is used by a libcurl that supports HTTP/2 to negotiate HTTP/2 support with the server during https sessions.

Note that this is the negated option name documented. You can use --alpn to enable ALPN.