That’s a pretty old unit. It’s not going offline. The message comes from the IoTaWatt because it cannot locate the app on the SDcard. My best guess is that given the age of the unit, the SDcard should be replaced.
You can try to copy the contents of your old card to the new, thus preserving your config and history. If that doesn’t workl, reformat the new card and follow these steps:
I would also recommend that you clear the “upload history from” date in your PVoutput setup. It’s taking hours to catch up after reboot because you are a free-loader and trying to upload redundant history.