Enable TLS 1.3 on Windows Server 2022

HTTP/3 support is an opt-in option on Windows Server 2022 via a registry key named "EnableHttp3" with value 1 at "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\HTTP\Parameters".
Running this command from an elevated prompt will create the key:

reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\HTTP\Parameters" /v EnableHttp3 /t REG_DWORD /d 1 /f

Then restart the http.sys service or reboot Windows to apply the setting.

It is likely the web service will need to advertise it is available over HTTP/3 as well using “Alt-Svc” headers in HTTP/2 responses (though this can also be done using HTTP/2 ALTSVC frames). This allows clients who connect over HTTP/2 to learn the service’s HTTP/3 endpoint and use that going forward. This is done by sending an HTTP/3 ALPN (“Application-layer Protocol Negotiation”) identifier with HTTP/2 responses advertising a specific version of HTTP/3 to use for future requests. Sending the ALTSVC frame can be done by http.sys. That can be enabled by setting the “EnableAltSvc” registry key with the command below.

reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\HTTP\Parameters" /v EnableAltSvc /t REG_DWORD /d 1 /f

After that run the following in PowerShell:

Enable-TlsCipherSuite -Name TLS_CHACHA20_POLY1305_SHA256 -Position 0

Finally, add the HTTP/3 response header to your IIS website. 

Under the HTTP Response Headers, add a custom HTTP response header with the following information:
Name: alt-svc
Value: h3=":443"; ma=86400; persist=1

After adding the response header, enabling the cipher suites and merging the registry keys, reboot your Windows Server 2022 server.