Latest Nginx with OpenSSL 1.0.2 still won't deliver http/2

Question

I have a server running Ubuntu 16.04 LTS with Nginx 1.112 built with OpenSSL 1.0.2h, and according a number of HTTP/2 support verficiation tools, like this one, the server is properly configured for HTTP/2 with ALPN. Yet in the latest Chrome (51.0.2704.106 (64-bit)), a reqest to the server returns with protocol http/1.1 and not h2:

I've read a number of posts here, like this one noting that Nginx built with OpenSSL versions pre 1.0.2 do not support ALPN. But I am running 1.0.2h.

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.1 LTS
Release:    16.04
Codename:   xenial 

$ nginx -V
nginx version: nginx/1.11.2
built by gcc 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.1) 
built with OpenSSL 1.0.2h  3 May 2016
TLS SNI support enabled

$ openssl version
OpenSSL 1.0.2h  3 May 2016

Qualys SSL Labs 'SSL Server Test' gives the domain an A+ SSL rating. I used Let's Encrypt to create the cert, via the method referenced here.

Could it still be an Nginx certificate configuration issue?

Any and all help greatly appreciated.

Answer 1

After all that, I was able to discover that it was a local issue. My antivirus application, Avast Mac Security, was preventing the protocol upgrade. Disabled it, and h2 is used.

BazzaDP's answer on this question is what led me to discovery:

Why HTTP/2 on a specific site works in FF, but doesn't work in Chrome, IE and Edge on the same Windows 10 computer?