full description of the error:
The Web server (running the Web site) is currently unable to handle the HTTP request due to a temporary overloading or maintenance of the server. The implication is that this is a temporary condition which will be alleviated after some delay. Some servers in this state may also simply refuse the socket connection, in which case a different error may be generated because the socket creation timed out.
One thing that can happen on your server is that all 80+ ports the server receives taking precedence over port 80. The same port your website runs on.
Here's a command to see if this is true (run it in
netsh http show urlacl
if you get an entry something like this:
Reserved URL : http://+:80/
Then this means that the above issue is happening to you. And you need to remove the record from there with this command
netsh http delete urlacl url=http://+:80/