Docsis

I want to know wich Docsis Xfinity is using,3.0 or 3.1?,thanks in advance for any answer.Recently I

received an email saying  my equipment is not up to speed ,that my equipment needs to be upgraded.My current modem is a Arris Docsis 3.0.I ordered a Netgear Nighthawk Docsis 3.1 just

in case.