I have Nginx (1.9.12) setup and working fine with HTTP/2 on host-a. I can establish HTTP/2 connections to host-a with any web browser. I also have HTTP/2 and proxypass setup on host-b. I can proxy HTTP/1.1 requests from host-b to host-a with any web browser. I can also establish HTTP/2 connections with host-b using any web browser. However, I can't get the proxy request from host-b to host-a to talk HTTP/2. The connection between host-b and host-a doesn't utilize the TLS ALPN extension so that the h2 protocol can be used. A packet capture shows that HTTP/1.1 is used for the proxy connection between host-b and host-a despite the fact that virtual host on host-a is configured to only accept h2 connections. Is there a way to force the use of the TLS ALPN extension?

Thanks for your time,
Russel