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amitramani's profile

New problem solver


22 Messages

Saturday, December 27th, 2014 2:00 PM

Using your own wireless Router with the DPC3939B modem?

I would like to disable the Wifi ability of the DPC3939B device altogether. I have had issues with devices dropping off the WiFi. It happens often enough.


Comcast technicians have come and spent several hours trying to determine the issue. At first, they said it was my 2.4GHz cordless phone. I have replaced it with a DECT 6.0 as recommended by one of the technicians. 


At this point, I am ready to disable the Wireless ability of the DPC3939B completely and use my own Wireless Router.


Are there any guides/instructions on how to set up this connection? I understand I will have to connect the DPC3939B to my D-Link Router via an Ethernet cable. Is there any other special settings required?


Trusted Forum Contributor


113 Messages

9 years ago


If you're having issues with wireless dropouts have you analyzed the environment for obstructions, faraday cage conditions etc


Most modern smartphones can be used with a network/wireless analyzer to examine the wireless signal within an environment to see if you have noise causing an issue outside of the wireless router.


My house for example was built in 1928 and the walls have chicken wire through SAC 4 masonry. If I place an access point in one room, no other room can access that WIFI. Only the attic and the basement directly above and below that room.


I’ve resorted to 3 UNIFI access points in the attic which cover the entire outside of the property (Being so high it actually goes out 1 and a half blocks in a 360 degree pattern.


They reach two floors into the basement and the walls are not an issue as there are plenty.


Have you confirmed that the wireless drops out in the same room that the comcast CPE resides? (Customer premises equipment).


I would consider a single Unifi access point (They range now about 60 bucks for a 2.4 and not much more for 5ghz as well as AC versions).



1.4K Messages

9 years ago

Hello amittramani and welcome,


If you have experienced devices dropping off the wired or wifi there is an easy solution to this. Log into your DPC3939B, username=cusadmin/password=highspeed, the go into your LAN and edit this so that your LEASETIME paramter is set to FOREVER. This will establish any wired or wifi connected device to stay connected until you shutdown the connected wired or wifi device.


Hope this helps you out.



New problem solver


22 Messages

9 years ago

I have checked my environment multiple times by disabling all potential sources of interference. When this problem happens, I am unable to connect to the WiFi with any device, whether it be laptop, PC or a smartphone. 


I can stand next to the DPC3939B and it still will not connect to the WiFi.


After 1 full week of disabling the XFINITY WiFi, I am pleased to report that my problem has not returned. i.e. no more dropping the WiFi.


Comcast should figure out why this Public WiFi/XFinity Wifi somehow has an adverse effect on the signal of the Private WiFi. 


My problem has been addressed. So at this point, I no longer need to use a separate standalone WiFi router.