s33 eero 6+ not connecting

As you had mentioned two Internet Service Providers which is Atandt and Xfinity at your place. Usually only one Internet Service Provider is required to activate the modem so please provide us more information to guide you further.

S33 is connected to xfinity not Att

after like 3 hard resets 

multiple power cycles eero and xfinity s3 worked

Great, so your Internet service provider is Xfinity and internet works fine and you have router connected to S33 so make sure the setup is perfect and monitor connection if any issue on modem reach out to Arris.com/consumersupport