Constant disconnect/reconnect, bug?

I get constant disconnects and subsequent reconnects with LTE Base HAT and a Verizon SIM.
I have added logging to, and it shows endlessly reconnecting every second. Strangely, restarting fixes this temporarily - but it continues again after restarting qmi_reconnect.service.
This makes me believe that it’s a software problem, but I have no way of verifying this other than that restarting clears whatever goes wrong.