Recently I use Apache2 to build a website on my Ubuntu 18.04 machine. I can successfully access my website via both IP and domain through the server itself and other devices under the same network. However, I cannot visit my website through cellular networks. This is my website domain: doubilab.com. This is my IP: 131.128.54.59.
The status of the Apache server is as follows: Apache2 Status
Notice that the firewall is inactive.