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Remote Deskop Connectivity

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Remote Deskop Connectivity

I am experiencing a set up issue with the new modem a Comcast technician installed today (01/04/2016).  I am attempting to set up the remote desktop feature in the router for port forwarding and have been unsuccessful.


I have accessed the router's advanced functions via the Comcast  log in feature in the router to complete the port forwarding,

setting the ip address to the newly assigned IPv4 address, however I am still not able to access the host computer from the remote computer.


The remote desktop access was working properly prior to the modem change. No settings have been made or altered  in the windows remote desktop setup features (Windows 7) since the new modem has been installed.  Comcast has pinged the modem and indicates all connections are working properly.


I am open to any ideas, or would like to know if anyone has experienced the same issue.  




Trusted Forum Contributor

Re: Remote Deskop Connectivity

Hello bob2 and welcome,


You must first determine what Remote Device Address was being used before you has the Comcast Gateway (CG). You must  use a Comcast Gateway (CG) DHCP non-dynamic IP or a static IP for this device. If you have a DPC39XXB CG and do not have any static IP address, then log into the CG, go to gateway.connections.LAN or LAN Status and change the starting DHCP address from to; click save settings for this to stick This will make your dynamic ip address range from to and leave you with static local addresses between through


I recommend that you setup your remote device to use in its network configuration and use gateway address as and subnet mask at if you need to force feed. Now go to Advance settings and make sure the Remote Access Device port number ??????? is open / forwarded and then you should be able to consistently remote login.


Hope this helps you out.

Forum Contributor

Re: Remote Deskop Connectivity

Call comcast support back again and have the tech confirm that the bootfile which is being sent to your modem matches the model number of the modem.  If the modem gets a bootfile that is incorrect it can put it into a state where it kind-of-works to where it appears you have setup the interface properly for forwarding but it isn't actually doing anything.


I assume you have turned off the firewalling on the Comcast modem, and your using a static LAN IP on the windows 7 box not DHCP, the port forward is to 3389 and there are no typos, etc?


Re: Remote Deskop Connectivity

I have also had this same would be simple on any other router problem for a year now ever since using the DPC3939B.
Monday I will have to follow the advice given here.
Yes, I know I can bridge it and use my own router, but was hoping to keep it simple and less points of failure...but seems the DPC3939B is one big failure so far. Comcast phone tech support also useless with their solution which wasn't.

Why cannot Cisco / comcast just fix the firmware so we don't have to deal with problem which is simple on other routers???

Re: Remote Deskop Connectivity

After talking to comcast, they could not help.

I am wondering if it in fact may be something on my end not letting me remote in externally via public ip address? I am using Windows Server 2012 R2 Essentials (Active Directory) and the Microsoft RDP app for android.
I can remote locally, but not externally. I get a PC-NAME mismatch each time along with certificate trust thing? Where internally, I don't get the PC-NAME mismatch but the certificate trust thing.

Maybe this problem has something to do with all of this? I am also going to try to bridge the dpc3939b and use a asus AC router and open port 3389 to rule things out.

Re: Remote Deskop Connectivity

Have you personally experienced this solution with this doc3939b modem? Yes this should work fine with other modems without this simple problem, but seems this particular model is a LEMON.
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