I have been searching for a long time and not found a workable solution to my requirement yet so hoping someone can help.
I have an existing project running on an Arduino Uno and connecting to an ESP8226 via serial. I use this serial link for monitoring, control, config and debugging (sending and receiving strings). The Esp is running Esp-link firmware meaning I have access over wifi to serial console etc.
All was well when I was building/testing this at my home on the same WiFi. But I am now about to deploy this at a very remote site where the WiFi will be replaced by a MiFi device (like a mobile 4G wifi dongle - MiFi - Wikipedia) meaning I now need a way to connect to this remotely over the public internet. This remote access will not be required eventually but will for a few months for final testing in-situ. Security is also not a major concern at this point as this is temporary and low risk.
All the potential solutions I have read about involve making the Esp8226 directly internet facing using static IP address of WiFi and port forwarding. But with the MiFi none of this will be possible as its just locked down.
I was thinking the easiest solution would be to flash something on the Esp that just forwarded its inbound serial comms (from the Uno) to an MQTT server as MQTT messages and subscribed to another MQTT channel to receive serial comms remotely and forward this as real outbound serial comms to the Uno. But it seems nothing like this exists that I can find already or only in 1 direction.
Any pointers here would be much appreciated. I cant be the first...