How to establish an HTTP/2 TLS connection with BIG-IP when the client does not support ALPN

Hi everyone,

I have been working on HTTP/2 project and have run into an issue that I'm struggling to understand or solve. I was hoping someone here could provide some guidance or advice.

Here is the information on my setup:
I need to establish HTTP/2 communication between the client and LTM.
The client does not support ALPN

In the article "K47440400: Overview of BIG-IP support for HTTP/2, h2c", it is mentioned that:

GET / HTTP/1.1
Host: server.example.com
Connection: Upgrade, HTTP2-Settings
Upgrade: h2c

Therefore, I believe that if the client does not support ALPN, it can establish an HTTP/2 connection with the server, but without using TLS.

So, can the client still establish an HTTP/2 connection with the server using TLS if it does not support ALPN?

I would greatly appreciate any suggestions, advice, or insights that anyone can provide. Thank you in advance for your help!