Z-Wave has stopped functioning properly

I'm scratching my head as to what could have happened. I'm not aware of any change having been made to my Indigo 2021.2 server running on Mac OS Monterey 12.2.1. I noticed yesterday that a trigger that turns a Z-Wave relay off and on didn't work. Today I investigated, and I found that although Z-Wave devices are able to report their status information in to Indigo, Indigo doesn't seem to be able to send instructions to any of the devices any more.

Log entries look something like this. At 2:08:09 I unplugged and then plugged in a Z-Wave relay switch. Indigo immediately received the status message from the module.

Jun 23, 2022 at 2:08:09 PM
Z-Wave received "Office Fan Switch" status update is on

Then 20 seconds later I executed an action that is supposed to turn it off and on. Indigo wasn't able to communicate with the module.

Jun 23, 2022 at 2:08:29 PM
Trigger Office Fan Reset
Z-Wave Error no ack/nak/busy reply (013) for setRelayValue (re-sending)
Z-Wave Error no ack/nak/busy reply (013) for setRelayValue (re-sending)
Z-Wave Error no ack/nak/busy reply (013) for setRelayValue (re-sending)
Z-Wave Error send "Office Fan Switch" off failed
Schedule Office Fan Reset (delayed action)
Z-Wave Error no ack/nak/busy reply (013) for setRelayValue (re-sending)
Z-Wave Error no ack/nak/busy reply (013) for setRelayValue (re-sending)
Z-Wave Error no ack/nak/busy reply (013) for setRelayValue (re-sending)
Z-Wave Error send "Office Fan Switch" on failed

This is happening with all of my Z-Wave devices. Is this a symptom of some well-known scenario? It has been working just fine for a couple of years now, and I'm baffled.

[jay (support)]

Have you unplugged/replugged the Z-Wave interface?

Let me try. The computer reboots every couple of days, so I didn’t think that was the issue.

That fixed it. I'll keep an eye on it and see if it recurs.