Using URL https:...:8181 fails

[Only-a-Rookie]

After a colleague successfully installed Restreamer2 on a Windows Server 2022 with Docker Desktop (successful access to the domain: http:// ...:8080), I am now supposed to perform the secured access with a certificate via https:// ...:8181.

In the advanced network settings, I have set port 8181 for HTTPS.
The checkbox for the Let's Encrypt certificate is marked.

According to netstat, restreamer2 is listening on ports 8080 and 8181

What else do I have to do ( probably on the Windows level)? I read something about port forwarding, but I can't get it to work.

[utilsites]

If I remember correctly, to use letsencrypt you have to enable port 80 to that service be able to validate site domain and generate ssl certificate.
Check Restreamer documentation also.