It sounds like your web app may be blocked by a firewall or network restriction on cellular data. Some cellular networks may block certain ports or protocols for security reasons.
To troubleshoot this issue, you can try the following steps:
Check if the issue is specific to your web app or if other web apps are also not working on cellular data. If other web apps are also not working, then the issue may be with the cellular network.
Check if your web app is accessible from a different cellular network or from a different device on the same cellular network. If it is accessible, then the issue may be with the cellular network or device.
Check if your web app is accessible using a different port. Some cellular networks may block certain ports, so you can try using a different port to see if it resolves the issue.
Check if your web app is accessible using HTTPS instead of HTTP. Some cellular networks may block HTTP traffic, so using HTTPS may help bypass the restriction.