The Sonos Amp is to be used for outside speakers. I think it maybe to far to grab the wireless internet connection.
Best answer by UKMedia
Can you expand upon '....but struggling to connect it to the system.'?
I assume that you have connected the Amp to the same router as your Wi-Fi? You should be able to select 'Add Player or Sub' under Manage but the issue you might have is that connecting a single device via an Ethernet cable puts the Sonos system in Boost mode rather than 'Standard' Wi-Fi.
Are you able to connect any of your other Sonos players via an Ethernet cable? If so, then please remove your Wi-Fi credentials within the Sonos app and select 'reset'. Please see this article: