Automatically switch to Hologram when Ethernet goes down

[kfxkaplan]

I’m running a system on a headless Raspberry Pi where we primarily have ethernet connectivity, but want to automatically swap to a Hologram SARA-R410M upon loss of ethernet connectivity. I’ve found several sources that say NetworkManager is a good way to do this, but haven’t had much luck getting it to talk to the Hologram, though it is able to detect the modem. Does anyone have experience with a setup like this, and how did you approach it? I’d prefer using an existing tool for this rather than writing my own script to call the Hologram Python SDK, if possible.