I'm forwarding port 80 of a web server to the public interface of the firewall, which is then mapped to a domain name so that the server can be accessible from that domain name.

I did this process too many times but this time I'm in a different country and connected to the internet using a different kind of firewall.

Conditions:

1. When I try to access the website from any other networks, it shows "Connection timed out"
2. I can verify that nslookup theDomainName.com maps to the correct IP adderss.
3. I can veryfy that the website is accessiable from inside the local network.
4. When I apply the exact same configurations while only using any other port other than port 80, everything works fine.

So, I can tell that something is blocking the trafic sent to port 80. This can either by:

1. Port 80 is blocked by my ISP (Which is very likely in my current location)
2. Something in the firewall is reserving port 80.

The point is, I don't want to guess. i need a practicall experiment that can narrow down the possibilities, something like trecert but for port blocking.

Any suggestions?

ISP blocking ports

ISPs these days block used ports and 80 is the HTTP one which is the most common used port and protocol.

If you want details for blocked ports, contact your ISP.

OS Firewall Issue

If you have configured your firewall rules correctly and it doesn't work, check your server's OS firewall rules. Also make sure that the OS rule is Inbound and Outbound.

Protocol Issues

Make sure if the rule uses both TCP and UDP.

Router/External firewall issue

It may have problems. Update the firmware of router/external firewall.

Wrong Configuration

Make sure if the IP address is correct and matching the server. Note: The address may change.

Use any other port

If it still not working, just use any other port.

I hope that helped