Enable HTTP/2 on WCF and Web API

问题

I tried to enable the HTTP/2 on my IIS 10. i used this tutorial in order to do that. after enabling HTTP/2 i tested my server with various clients and even online websites like these:

1. https://http2.pro
2. https://tools.keycdn.com/http2-test

all result indicates that server supports the HTTP/2. when i log the request with my IIS i can see the protocol version is 2 but when i log the request on my application (wcf and web api) it shows HTTP/1.1!! now i wonder what is the problem? do i miss something or what?

NOTE

1. during the test i realize i have to restart whole IIS after disabling and enabling HTTP/2 feature. which founded little odd.
2. when i send the HTTP/2 request with fidller i get 505 error.
3. for internal loging i use log4net and log the SERVER_PROTOCOL like this: HttpContext.Current?.Request?.Params["SERVER_PROTOCOL"]
4. this my api if you want test it: here

来源：https://stackoverflow.com/questions/58604331/enable-http-2-on-wcf-and-web-api