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Member Since: ‎03-16-2012
Posts: 1
Accepted Solution

Authentication Failed Router

I am trying to log into the modem/router but I continue to get authentical failed.


I have reset it, held for 10, 15 and even entire minute. I unplugged it, reset it and still I continue to get failed authentication. I am using:





I have an Xfinity Arris Modem.

Posted by
Networking Expert
Member Since: ‎07-28-2003
Posts: 24,238

Re: Authentication Failed Router

[ Edited ]

Exactly what model of modem, router, or gateway do you have?  From your vague description, it could be a lot of different things.  Can't say for sure until we know exactly what you have.


If you have one the Xfinity Wireless Gateways (like the SMCD3GNV or the Arris TG852G/CT), then to properly reset the device, remove the Ethernet cables and coax connection and then press and hold the recessed Reset button for more than 15 seconds.  That should reset it to defaults values defined by the firmware, which means it sits at the default userid is "admin" and the default password is "password".  If those aren't working and you are SURE you have one of the Comcast provided gateways listed above, then either the device is either malfunctioning, or it's in some unknown state.  You can try calling the gateway support folks at 800-363-2416 and see if they can get into the gateway and correct the problem.  If not, you will likely have to replace it.  If and when you do that, do NOT get another gateway if you can avoid it, get a simple cable modem (ie. EMTA if you have Xfinity Voice) and get your own decent router and never use a gateway again, they are nothing but trouble in MANY situations.  The other option if you get a replacement gateway is to have the gateway support folks (see number above) place the gateway in bridge mode, and again run your own wireless router.


I have heard of some number of Xfinity Wireless Gateways not resetting to factory defaults properly and although the exact cause and circumstances were never explain to my satisfaction, the end result is the gateway was bricked and needed to replaced.


If you have something else, you need to be more specific about exact make and model, etc.

Posted by
New Visitor
Member Since: ‎01-10-2014
Posts: 1

Re: Authentication Failed Router

You Rock, Totally fixed my problem, admin password.... man thanks

Posted by
Connection Expert
Member Since: ‎12-24-2003
Posts: 47,393

Re: Authentication Failed Router

Year and ten month old thread closed.