Context

I try to enable HTTP/2 through my nginx configurations:

server {
  listen 443 ssl http2;
  listen [::]:443 ssl http2;
  server_name stg.grozissaviems.lt;
  ssl_certificate /etc/nginx/certs/stg.grozissaviems.lt.crt;
  ssl_certificate_key /etc/nginx/certs/stg.grozissaviems.lt.key;
  ssl_protocols TLSv1.2;
}

Issue

When I run curl -I -L https://stg.grozissaviems.lt to debug HTTP/2:

• through my laptop terminal (MacOS) I see

    HTTP/1.1 200 OK
    Server: nginx/1.21.1
    Date: Mon, 26 Sep 2022 08:11:07 GMT
    Content-Type: text/html; charset=UTF-8
    Connection: keep-alive
    Vary: Accept-Encoding
    X-Powered-By: PHP/8.0.23
    Cache-Control: max-age=0, must-revalidate, private
    pragma: no-cache
    Expires: Mon, 26 Sep 2022 08:11:07 GMT
    Link: </build/fonts/Quicksand-Bold.ttf>; rel="preload"; as="font",</build/fonts/Quicksand-Light.ttf>; rel="preload"; as="font",</build/fonts/Quicksand-Medium.ttf>; rel="preload"; as="font",</build/fonts/Quicksand-Regular.ttf>; rel="preload"; as="font",</build/fonts/Quicksand-SemiBold.ttf>; rel="preload"; as="font"
    Strict-Transport-Security: max-age=31536000
  

• through my VPS terminal (Ubuntu) I see

    HTTP/2 200
    server: nginx/1.21.1
    date: Mon, 26 Sep 2022 08:11:36 GMT
    content-type: text/html; charset=UTF-8
    vary: Accept-Encoding
    x-powered-by: PHP/8.0.23
    cache-control: max-age=0, must-revalidate, private
    pragma: no-cache
    expires: Mon, 26 Sep 2022 08:11:36 GMT
    link: </build/fonts/Quicksand-Bold.ttf>; rel="preload"; as="font",</build/fonts/Quicksand-Light.ttf>; rel="preload"; as="font",</build/fonts/Quicksand-Medium.ttf>; rel="preload"; as="font",</build/fonts/Quicksand-Regular.ttf>; rel="preload"; as="font",</build/fonts/Quicksand-SemiBold.ttf>; rel="preload"; as="font"
    strict-transport-security: max-age=31536000
  

When I debug it using this KeyCDN tool I see:

HTTP/2 protocol is supported.

ALPN extension is supported.

When I access the website using Google Chrome, in the Network tab I see:

stg.grozissaviems.lt 200 http/1.1

Quicksand-Bold.ttf 200 http/1.1

Why does it differ?

CodePudding user response：

I finally found the issue. According to this answer:

You are using anti-virus software and it is MITM your traffic and so downgrading you to HTTP/1.1. ...

I did turn my anti-virus off and I could finally see HTTP/2 in the Networks tab!

In case someone stumbles upon my question and turning anti-virus software does not help, check this answer for more solutions.