Honeywell Z-Wave+ Light Switch Stopped Responding - how to diagnose?

Hi,

I have a zwave device which used to work great but recently stopped responding (not related to any hub updates). I had been using it fine for a while now.. leading me to wonder - what can I do to diagnose what's wrong?

The first time it happened - I excluded and re-added it.. again, it worked for several days before no longer responding.

I thought maybe it was out of range.. the device is on the outer edge of all my network. So, I bought a range extender but that hasn't helped either AFAIK. I've also done the whole zwave discovery a few times and let that sit for days..

Any ideas what I can try? Since my hub (C5) doesn't have WIFI I can't just move it close to see if that's the issue.. and my switch is hardwired so same problem there.

I was looking at the device info pages for the switch and the extender to try and figure out if the switch was using the extender.. how can you tell? I see the inClusters section but not sure what that relates to..

Just looking for some ideas!! thanks in advance

ps: device info
https://www.amazon.com/gp/product/B07B3LY1SJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

extender info