I have a couple of Balena devices running on the other side of the country and are connected to the internet via a 3G dongle that creates a wifi hotspot.
Over the last couple of months, this dongle has been using around 5x the expected amount of data. My initial feeling is that someone has gained access to the network. So far the dongle has used a total of 3GB this month - normal usage is around 600MB per month.
We have no access to the dongle itself to make any changes, so are trying to use the balena device to scan the network for unauthorised devices.
I read online about using nmap to check connected devices, but as these are remote, and I am not the most confident with command line operations, I thought it would be best to post here for some guidance.
What are the recommended steps for debugging high network usage?