EAX80 - internet keeps dropping

I mostly use my range extender to connect my icare (hot tub chemical monitoring system).  It's been great from last November until about 2 months ago.  the Icare was not connecting - although other nearby devices seem to connect.  the Icare was replaced and it's still having this problem.  It connected once last night and then dropped off again.  I can't get a handle on whether the EAX80 is disconnecting everything but it could be - the other device regularly connected is the garage which isn't used often and I recently noticed once I could not connect to it.

So I guess this is my long way of asking - how do I determine if the nighthawk is working properly?  I checked my home router and it is connected every time I notice an issue so I think the issue is from Nighthawk to devices (rather than Router to Nighthawk).

Thanks.

Also - it says firmware is up to date.