I had a 4G modem with a web interface many years ago. It was flaky and would often hang. I just had a raspberry pi on my network pinging some known address, if it failed for long enough it’d replay the commands to restart the web interface.

If I’d have the same problem today I’d probably have home assistant power cycle the router with a smart plug.

I set it up during the outage last week.

Easy enough to just pull in the synapse docker container and run it on my home server. I wireguard it to my VPS that acts as a reverse proxy.

Both federation and push notifications work.