Install docker production-ready, working fine, but browser extension not connected

[x09]

1. Install docker production-ready service.

2. Edit .env (API_HOSTNAME=xsync.my-local-domain.tld )

3. Add dns record to DNS, hostname resolving fine for any clients

4. docker-compose up -d without errors

5. On client workstation go to https://xsync.my-local-domain.tld
   

6. Install browser extension https://chrome.google.com/webstore/detail/xbrowsersync/lcbjdhceifofjlpecfpeimnnphbcjgnc?utm_source=chrome-app-launcher-info-dialog - switch service to https://xsync.my-local-domain.tld and get Unable to connect

telnet xsync.my-local-domain.tld 443 connected

why browser extension not working? What i can do wrong?

[nero120]

Right click in the extension window and click "Inspect", can you copy here what you see in the console window please?

[SmartHamburg]

@x09 There is an exclamation mark in your browser screenshot. Is it possible, your browser is complaining about the certificate?
I tried a self signed cert without success and it worked after I requested and installed a Let's Encrypt cert.
Maybe there is some kind of certificate validation?