Thank you very much for the detailed response! I highly appreciate your help and support.
After running sudo netstat -tulpn I see the below
Why I don’t see any processes on ports 80 and 443? Because I run:
sudo fuser 80/tcp
I saw two processes, I run:
sudo lsof -t -i tcp:80 -s tcp:listen | sudo xargs kill
echo kill $(sudo netstat -anp | awk '/ LISTEN / {if($4 ~ ":80$") { gsub("/.*","",$7); print $7; exit } }')
But even when these processes were running, the website was not accessible.
My webserver (i.e. Nginx) correctly points to my WordPress files. So the answer to the second question is yes.
The SSL is valid and properly configured. The answer to the third question is also yes.