I am new to Ubuntu and I have setup Jitsi on server running Apache on Ubuntu 20.04 following a tutorial LINK.

During installation process when I ran command sudo /usr/share/jitsi-meet/scripts/install-letsencrypt-cert.sh it gave me error:

The following errors were reported by the server:

Domain: example.mydomain.com
Type:   unauthorized
Detail: Invalid response from
http://example.mydomain.com/.well-known/acme-challenge/oXTK_UVwJ_NBM7qF7bjZ2B5slKo67tvto70tmNWRWZ0

Though, when I go to https://example.mydomain.com/ it works fine and takes me to Jitsi page. I just have to authorize that I understand its an untrusted url.

I have searched on Google and found it could be due to port 80 no open

Below is the screenshot for my server firewall:

Also some said that it could be because of LetsEncript not being able to access server or blocked in firewall.

Please help.