Network UPS Tools - NUT sensor stopped working

Running Home Assistant v0.103.6 via Hass.io on Linux Mint 19.3.

I had integration with three NUT servers working well. Recently all three have stopped working. I’m not exactly sure when, but it might have been when I updated to 0.103.6 via the Updater. The failure definitely occurred within the last week or two.

I get the following three lines repeating in home-assistant.log:

2020-01-14 09:22:47 ERROR (SyncWorker_4) [homeassistant.components.nut.sensor] Failure getting NUT ups alias, Socket error.
2020-01-14 09:22:47 ERROR (SyncWorker_4) [homeassistant.components.nut.sensor] NUT Sensor has no data, unable to set up
2020-01-14 09:22:47 WARNING (MainThread) [homeassistant.components.sensor] Platform nut not ready yet. Retrying in 180 seconds.

I thought it possible that a Mint update caused this, but one of the servers I’m monitoring is on a Synology NAS, and there has been no update to that device in some time.

Running “upsc -L <server_name>” and "upsc <[email protected]_name> on the machine running Home Assistant both works as they should, as does the graphical tool. It looks as if something changed in Home Assistant.

I haven’t seen a similar complaint posted … where in my installation can I look for more clues?

Thanks.