Interesting, the app shouldn’t be telling you that, unless it is a CONNECT:AMP. You’d just want to bond the Amp to your Arc (which must have Wi-Fi on) via the app. See the setting up Amp or CONNECT:AMP as surround speakers FAQ. 

Hi @akol 

Welcome to the Sonos Community!

How far apart are your Arc and Amp? They should be in the same room.

@Airgetlam it took a little bit of troubleshooting. I had to unplug the amp from ethernet and connect it via wireless and then it worked. Thankyou

@Corry P there are in different rooms and probably 30 to 40 ft apart.

The one thing to remember here is that the Arc is sending a 5Ghz signal to the Amp, over which that surround signal is carried. And 5Ghz is more sensitive to obstructions that 2.4Ghz. However, as it’s running now, I’m pleased, just wanted to provide that caveat. 

@Airgetlam so the signal doesn’t go over home wifi?

Technically, ARC is using WiFi to communicate with the AMP, but it is a private 5GHz link that is not available to your other WiFi clients. The private link is susceptible to the usual sources of interference.