Hi, I have a Debian VM running Node-Red, mySQL, Apache and PHP.
On my Smartphone side I have an App developed with Kodular that interacts with Node-Red
If I connect my Android to my local WiFi everything works perfectly but if I disconnect WiFi and use the Cellular network nothing works, not even an http request reaches the VM.
No service on the VM is available to Android except if it is connected to the WiFi.
Relevant Firewall ports on the VM are allow 0.0.0.0/0.
Assistance welcome.
Thanks
On Google Cloud Platform, I suggest verifying if there is another conflicting (deny) firewall rule that has a higher priority as per this document. Though, it is not clear from the description where the application is running such as if on the phone or in the Cloud. I assume here that you are connecting using Public IP addresses, and not local hostnames/domains or internal IPs. I suggest verifying this with the involved apps.
Another possibility is that your phone carrier does not allow certain connections on some ports. Hence, the application on the phone is not reaching the cloud instance. Maybe using a third party VPN service could bypass it.
For debugging, I suggest utilizing tools such as tcpdump while attempting to connect (both ends). Though this might be complex on the phone, and tethering to a laptop might be needed. For further help, I suggest posting on Stackexchange or the community sites for either Kodular and Node-Red with all error messages from the apps and a detailed explanation of the configs. To explain, this community forum is meant mostly to answer general questions about the product. For troubleshooting GCE/GCP issues, we recommend using Stackexchange.