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4 Messages

Saturday, September 6th, 2014 8:00 AM

Help configuring a static IP with DPC3939

My company has recently switched from DSL to Comcast Internet but we have been experiencing problems with the Comcast service since day 1. The technician came out to install and verified that we had internet service, no issues but after a few days all users on the network were reporting intermittent internet drops. For .5 seconds the connection would vanish, booting us from remote desktop sessions, email etc... This drop happens 2-3 times per hour.

 

We had the Comcast technician return and he explained that a static IP address would likely fix all of our issues. He explained that, despite showing 100% uptime on his end, the drop in service was probably caused by the modem's dynamic IP setting fetching a new IP address which would explain the temporary drops with service being restored immediately. 

 

We complied and ordered 1 static IP address and it has just been installed. As expected, Comcast is offering absolutely no support in helping to configure the IP (despite the fact that both the modem and router is leased from them and that our service is unusable without it). Here is the info for the static IP:

 

Usable IP for internal: 50.252.144.xxx

Comcast gateway modem: 50.252.144.xxx

Subnet mask: 255.255.255.252

Primary DNS: 75.75.75.75

Secondary DNS: 75.75.75.76

 

My question is, how do I configure this to work with the DPC3939? I have already tried http://10.1.10.1/ --> Advanced --> Static Routing and entering some of the data but I get the following error "Failed, please try again later.
Message: Gateway IP must be reachable. Netmask must match route address."

 

I am now stumped. We do not need the static IP to login remotely from outside the network, just so that our modem/router has a static and stable IP address to prevent the intermittent service drops.

 

Any advice would be much appreciated.

 

Sincerely,

Jeffrey

New Member

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4 Messages

10 years ago

Small correction, we are using  "Model: Cicsco DPC3939B"

Advocate

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1.4K Messages

10 years ago

Hello jmgriffin and welcome,

 

First, Comcast has installed the DPC3939B (DPC) StaticIP into that Comcast Gateway. You can look at this by logging into the DPC through any computer connected to any of the rear LanPorts 1-4, bring up a Browser, type in 10.1.10.1, then username=cusadmin, password=highspeed. Then click on connection, then WAN or WAN status and you will see the StaticIP Gateway address and subnet mask, DNSs, etc. 

 

Second, if you need to program your static IP into one of you devices like webserver, camera server, etc., just go into that device's wired network configuration (this is usually within the NIC adapter TCP settings) and click on Static IP, enter in your Static IP Routeable, Gateway, SubNet Mask, DNS addresses, save then reboot this device. You must make absolutely sure that this device in Enet cable connected to any of the DPC LanPorts 1-4 interconnects. After you reboot this device you should be able to bring up a browser to access the Internet for starters.  The final test is for you to go up to the Internet on any computer and try to ping your StaticIP Routable Address. Ithese both work, then you are golden. 

 

Lastly, please be advised that if you want to use your Private and Public WIFI, it is mandatory that you keep your DPC LAN DHCP server enabled. 

 

Hope this helps you out.

Gold Problem solver

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610 Messages

10 years ago

so the "usable" static IP that Comcast gave you is intended to be configured on a separate router or server. the "Comcast gateway modem" address has already been assigned to the DPC. in general, you should not be experiencing drops, whether you have a static IP or a dynamic one, and i personally might question the accuracy of what that representative told you.

 

to start, when these drops in connection happen, does it happen for everyone simulatenously, or is it isolated to particular computers? also, are your machines/devices connected wirelessly or wired? if wireless, how far away are the machines from the DPC? as well, could you possibly post the signal levels from the modem (they are at http://10.1.10.1 -> Connection -> WAN Status (i think that's the wording of the menu options))

New Member

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4 Messages

10 years ago

"i personally might question the accuracy of what that representative told you."

 

I am begining to think more along these lines. What else could be causing this issue? Might swapping the DPC3939 hardware fix the problem?

 

Thanks,

Jeffrey

Advocate

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1.4K Messages

10 years ago

Hey jmgriffin,

 

If you are still seeing these intermittent drops, I would recommend you procede as follows:

1. Connect a computer to any DPC LanPorts 1-4 Enet interconnect, bring up browser, go to 10.1.10.1, then use username=cusadmin, password=highspeed.

 

2. Next click on Connection, then click on WAN or WAN Status to insure that  your Primary (75.75.75.75) and Secondary (75.75.76.76) DNSs are mannually assigned (programmed) in. If you make changes click save button.

 

3. Next click on LAN or Lan status, click edit and make sure the LeaseTime=FOREVER and DNSs are mannually assigned ( programmed) within. If you make changes clcik save button.

 

Let us know if you are still having issues.  Thanks.

 

 

New Member

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4 Messages

10 years ago

 VBSSP-RICH,

 

Thank you for the suggestion. I tried that but we are still experiencing the intermittent service drops. As a result most of our users have switched back to our DSL connections just so that we can continue to conduct business. I am thankful that we did not cancel the DSL immediately.

 

Do you have any other suggestions? I am very near contacting our Comcast sales rep to issue the cancellation orders on our service.

 

Thank you,

Jeffrey

Visitor

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1 Message

9 years ago

it issue happened to us,end up I have it replaced. as reason I finding that this new Comcast Cisco Modem with WIFI DPC3939B wouldn't support  Internet routable static IP address or using pseudo bridge mode for my case. I applied the same configured with previous NetGear Business Gateway Modem, it works like charm! therefore, don't use COMCAST Cisco Modem if you need routable static IP, unless you know how to make it works, then please share it.