Hi NaturaNate.  Comcast Equipment Engineering informed us that AP Isolation is hardware encoded on the Cisco device. As a result, a functional configuration of the Chromecast application via the WiFi interface on the Cisco device is not possible. Currently we do not have a timeline for change in hardware.  I apologize for any inconvenience this has caused. 

A configuration solution for the 3rd party Chromcast add-on application was posted in the Forum by Establish Member train_wreck, 

train_wreck

Established Member

Posts: 188

Registered: ‎11-03-2013

 

Re: Chromecast & Cisco DPC3939B AP Isolation Enforcement

http://forums.businesshelp.comcast.com/t5/Equipment-Modems-Gateways/Chromecast-amp-Cisco-DPC3939B-AP-Isolation-Enforcement/m-p/20945#M2359 

 

Do we still not have a fix for this?

Its mildly amusing how long it takes for this "quality" service provider to resolve such a simple issue.

Its one simple setting that needs to be changed, its called AP Isolation... but of course no one in tech support knows what that is so I had to escalate to teir two, and even they barely know what it is and suggest I spend my own money for hardware that supports it when their equipment should work just fine.

This isn't the case, AP isolation is built into the RADIO chip itself, it has nothing to do with anything in the code.  Cisco just used a radio chip that doesen't permit it.  If you get into the forums on the dd-wrt.com website and start searching for this issue you will find lists of chips that support it and ones that don't.  Until Google came out with Chromecast the only people screaming about the lack of this feature in radio wifi chips were the people on the dd-wrt and open-wrt forums, and do you think the radio makers listened to them?  Haw

January 30th and still no Fix???

And a quick update.

Comcast_John squared us away.  Phone support had disabled LAN DHCP, comcast_john placed us into True Bridge Mode (as opposed to the fake one) and now we've got internet and Chromecast working just fine.

moq, please read the entire thread.  You cannot fix a hardware chip with an operating system software update.  The hardware chip in this modem doesn't support this feature.  If you were handly with a soldering iron maybe you could fix it.  But I think you would need a surface mounting desoldering and resoldering station plus you would need to write a complete new microcode for the modem.  And yes this is rediculous as I'm trying to prove a point. 

You will need to replace the modem with a different model.