Is Insteon interface is dead or Indigo problem on Mac?

I have a really old Insteon PLM 2412UH (I'm guessing the "H" is because of the "HouseLink2 enabled" sticker that's on it from when they swapped out everything years ago). It's been working great until the last week or so.
Mac is Sonoma 14.2.1 and Indigo is 2023.2.

What's happening is that the PLM hears and reports on all the Insteon traffic in the Event Log, but no commands from Indigo work (on, off, status). I get failed messages in Indigo with "no acknowledgement".

Is there a way to figure out if something's wrong with Indigo/Mac vs. the PLM needs replacing (without buying a new one to see if it works)?

[jay (support)]

no ack messages are often a sign of signal noise. Does it happen for every command that Indigo sends or only some? I would recommend that you check read through the signal troubleshooting page and try everything there.

Thanks for the response. Interestingly, things are working again. So, either it was interference or the PLM is dying an erratic death. I don't know how old PLMs behave, but I have seen old Insteon devices get erratic. If it starts acting up again, I'll have to start paying attention as to anything that could be causing interference.