Sonos Amp shows (unused) not registered. Randomly happens

The first suggestion is DON’T factory reset, as at best this will achieve nothing.

Was the Amp your only wired device?  If so then you would have been using SonosNet and all your other devices would have boon connecting via the Amp.  If so, them no Amp means no system.

Edit: in what sense does it “randomly take down your system”?  Please describe what happens.

My best guess on the information provided so far is that the whole system rests on the Amp because it is the only wired device. 

For some reason this unit or its connection to the router is flaky. This could be something as basic as a dodgy Ethernet port or faulty cable.

Amp is only wired device. What I mean by randomly is that it stops working out of the blue but I am able to get it working by turning amp off and on again. Usually it is then good for a couple of weeks. 

Certainly agree with @John B, as it’s the only wired device, and consequently responsible for generating SonosNet, which all the other Sonos devices use to connect with. However, I’m wondering if there could be a duplicate IP address issue?

I’d really be tempted to test that theory by unplugging all Sonos devices from power, and rebooting the router. Give it a couple of minutes to reload the software before plugging back in all Sonos devices, including this Amp. 

But, as @John B states, it could be the simpler solution of a bad Ethernet cable or connection. 

If you still have the ZP-100 wire it to Ethernet and plug it back in, see if that keeps the other Sonos from going missing when the Amp has issues.

You could also temporarily wire any non Sub/surround to Ethernet to get the same result.

Good point. I do have it somewhere. I’ll hunt it up and try it if the other suggestions fail. Have to find it 🤣. 

I’ll definitely try that out. My Ethernet cable is plugged into a N1 in the wall. (The main router is in the far part of the house). Is it ok if I just pull the Ethernet cable out or do I actually have to do on the router. Reason is router in someone else’s house. Hope that made sense lol

Router in someone else’s house could make the issue extremely problematic, if my analysis is potentially correct. I’d certainly start with @John B ’s suggestion. 

Well tried a few things and managed to get the playbar and 2 out of 5 speakers working. Had an opportunity to reboot the router and now only the playbar works 🙄. 
 

if the playbar is working can I assume it’s not the Ethernet cable?  I’m beyond frustrated. But at least I can listen to music through the playbar. 
 

I’ll probably be moving into the main house soonish maybe next month and will be able to connect the amp directly with the router rather than the N1 connection. Hoping that will solve issue. 

No.  Check in the System settings in the Sonos app, under About my System.  Does it show WM:1 or WM:0?  WM:0 would imply connection by Ethernet here, WM:1 means it is connecting to WiFi.

But even that snapshot doesn’t completely rule out a dodgy connection causing intermittent problems.

It shows w1. 
 

thanks for that!  Will look at getting another Ethernet cable and giving that a go and see what happens.