Can't connect to gateway (openvpn) with latest firmware

Hi everyone, I have recently set up a new gateway with the latest firmware (1.3.1), and setup openvpn on it. I have approx 25 other gateways setup this way without any issues. I tested it over ethernet before deploying and openvpn worked fine. This particular device is communicating via mobile (sim card) in the field. it’s connecting to chirpstack fine, and uplink/downlinks are working fine. For some reason when attempting to communicate via openvpn whilst it’s in the field, I can’t connect. When doing a ping to that ip via the cli, it gets no response (although the ip is definitly created, and the ip shows on the gateway also).
I’m assuming there may be a firewall setting required with the new firmware? I did create one for port 1194 (tcp/udp), but this didn’t help and I haven’t had to do anything with my other gateways, they just work.
I have been to the device and logged in via wifi without issue, which also gives me a connection to the internet…
Any assistance would be greatly appreciated, hopefully it’s something simple!
Regards, Andrew.