unable to activate the modem SBG8300 by xfinity since no CM MAC number

  • 30 October 2023
  • 3 replies


Hello. My new Arris SBG8300 has WAN MAC and HFC MAC numbers but no CM MAC number. Xfinity wifi activation cannot continue without a CM MAC number. Any help?


Best answer by Xfinitydupe 30 October 2023, 14:16

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Userlevel 6
Badge +40

It should be the hfc mac that they use. 

Are you activating it through the xfinity app? 


I tried the HFC MAC number and successfully activated my modem thru the Xfinity app this morning. Thank you for the suggestion.

I spoke to Xfinity customer service for far too long last night. I gave them both the WAN and HFC numbers. They said I was activated but could not explain why me trying to login into the modem only resulted in a redirection to the Xfinity app to activate the modem. They concluded it was an Arris issue by not providing a CM MAC number. It seems they, like me, did not know CM MAC and HFC MAC are the same?

Thanks again.

Userlevel 6
Badge +40

Glad you got it working!

the app tends to be better/smoother versus calling them