I’m guessing you didn’t unbond the surrounds from the previous Beam before swapping it out for the new Arc. There’s two choices. You can temporarily reconnect the Beam, and the unbond the surrounds and any potential subwoofer, which will go into their own temporary ‘rooms’ until you bond them with the Arc, or, you can factory reset them to be ‘new’ speakers, and add them that way. Either would be acceptable, since you’ve already added the Arc, there’s no chance of losing any playlists, etc if they’re factory reset. 

Thank you Bruce! I actually returned the Beam so I will have to try the second option. Since I’ve added the ARC, will I have to factory reset that, or just the two surround sound speakers? 

Just the surrounds.

ok, I reset and then added them, But now when I go to re-add them as surround sound with my ARC, the light flashes white and then turns off? and then of course it tells me connection was unsuccesful

Hard to tell, have you read the LED states FAQ? I’d be awfully tempted to try a reboot of the router (and which router do you have?), as it sounds like the router doesn’t like the option of a proxied IP address. 

Of course, your best bet would be to  call Sonos Support directly to discuss it.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network. 

Is the Arc cabled to the network and have you perhaps switched off its WiFi? If so, then just enable it and try again.

Have you setup the Arc beforehand to work with the TV, Have you run the ‘TV Setup’ feature in the Arc room settings?

…or do you perhaps have more than one WiFi access point and might it be the case that the surrounds are connecting to a completely different access point?

OK, so I did the aforementioned once more, and then unplugged and re-plugged the surround sound speakers - and now everything is working. However, what is odd is that the surround sound speakers show as if they are off (no light at all) but they are working completely fine... Alls well that ends well I guess but this is odd.

There is a setting in the controller for the ‘room’ that allows you to turn on/off the lights on the speakers. They may be ‘confused’, try flipping that option on and off a couple of times to get them back to what you want. Note, however,  that the option is supposed to affect all speakers in that ‘room’, not just the surrounds.