IP address problem with Comcast Wireless Gateway

[Romney]

I recently moved to a new home and needed phone service for my alarm system. So I ditched my Motorola modem to use the Xfinity Wireless Gateway.
After about a month of use, we had a this problem with the modem.
We have 3 desktop computers that are hardwired to the modem and about 5-7 devices that connect wireless.
The modem went offline over night and when it came back up, none of the desktops would connect to the internet. Windows displayed unidentified network -no internet access.
Power cycled the modem, restarted the computers, still not getting connected.
replaced Ethernet cables and checked the IP address.
All of the desktops were getting IP addresses in the range of 192.168.0.x
Now, I know the IP address range of the gateway is 10.0.0.x, so these addresses made no sense to me at all. So I called Comcast for support. I was unable to get anyone to understand the problem I was having. The rep on the phone told me he would escalate the call to tier 2 but it could be 24-48 hours before someone could back to us.
So, instead of waiting, I decided to reset the modem to the factory default settings and start over.
Once I reset the modem, It took a while but we were able to go back through the set up process of set the networks back up. And everything started working again.
Later the next day, the tier 2 person called and said they fixed it. I said no, you didn't fix it, I did, I reset the modem to the factory default settings. We continued to argue for more than 30 minutes and she ended up hanging up on me because I told her she wasn't listening to me.
So, since, this has happened 4 times. on time number 3, I asked to have a tech come out and replace my modem. Of course, the tech didn't understand the networking problem that was occurring, and just replaced my modem. And it started happening again.
So, resetting the modem to the factory default settings corrects the problem but every time I do that, I have to reconfigure all of the smart devices I have connected to this POS modem/router.
And it becomes a huge hassle.
This issue really makes NO sense to me at all.
At the time the issues first started, 2 desktops were running windows 7, the other Windows 8.1. After we replaced the modem, we upgraded all three of the desktop computers. Replaced 2 MB's and processors. All are now running Windows 10.
We aren't running a 2nd router. We don't have a range extender. We don't have a DHCP server running on any of our computers.
And still, occasionally, we are getting incorrect IP addressing being distributed to our desktop computers only.
While all of this is going on, our wireless devices are working fine.
I believe its a firmware problem with the Comcast Gateway. But I'm reaching out to the community for help. Is there anything else that could be causing this problem?
Any help would be appreciated!

Thank you,
Romney

 

[Ralston18]

Please verify: your required/desired setup is that all your network devices, wired and wireless, use an DHCP assigned IP via the Xfinity Wireless Gateway modem/router. And that all DHCP assigned device addresses are to be 10.0.0.x where x is not .1 Applies to wired and wireless devices.

Is this the modem that you have:

http://media2.comcast.net/anon.comcastonline2/support/userguides/Wireless_Gateway_User_Guide_030811.pdf

Are you doing a normal reset or a factory reset (see Page 3 in the guide above.)

When you do a reset, either way, and access the modem configuration pages what default settings do you see: I.e., the Gateway is 10.0.0.1?

And that Gateway's default DNS (after a factory reset) is 10.0.0.1 - correct? (Trusting that Xfinity has remained "conventional".)

Do you know how to run "ipconfig /all" from the command prompt? I am interested in what the desktop wired adapters are seeing/looking for both when working and when the failure occurs.

 

[Romney]

Yes, all of my devices are using DHCP assigned IP via the Xfinity Wireless Gateway.
Yes, normally, all of the devices have addresses that are 10.0.0.x (Wired and wireless)
So, what I've been able to figure out is.. when our modem goes offline for an outage, we have a problem with our wired devices re-establishing the connection to the modem.
They are showing an IPV4 address of 192.168.0.x (where x is a random number between 2-254) .
The wireless devices are still connected with IP addresses in the 10.0.0.x range
The wired devices, in windows networking show, Connected to an Unidentified Network -No internet access.
The default gateway is 10.0.0.1.
The modem you listed is device I'm talking about. We've had to models of this modem. 1 arris and 1 cisco. They have the same Admin GUI to access the router.
When the modem is first set up, the network is 10.0.0.x and when I reset to factory default settings all the devices go back to that network.
I can run ipconfig /all but right now all of the computers have the correct IP address. So I'm not sure if it would do any good.
please tell me if there is anything else you need to know.

Thanks,
Romney

Please verify: your required/desired setup is that all your network devices, wired and wireless, use an DHCP assigned IP via the Xfinity Wireless Gateway modem/router. And that all DHCP assigned device addresses are to be 10.0.0.x where x is not .1 Applies to wired and wireless devices.

Is this the modem that you have:

http://media2.comcast.net/anon.comcastonline2/support/userguides/Wireless_Gateway_User_Guide_030811.pdf

Are you doing a normal reset or a factory reset (see Page 3 in the guide above.)

When you do a reset, either way, and access the modem configuration pages what default settings do you see: I.e., the Gateway is 10.0.0.1?

And that Gateway's default DNS (after a factory reset) is 10.0.0.1 - correct? (Trusting that Xfinity has remained "conventional".)

Do you know how to run "ipconfig /all" from the command prompt? I am interested in what the desktop wired adapters are seeing/looking for both when working and when the failure occurs.

 

[Ralston18]

Reference when the wired devices show:

"They are showing an IPV4 address of 192.168.0.x (where x is a random number between 2-254).

What DNS gateway are they showing and what subnet mask? If you ping or tracert that DNS Gateway what happens?

To be honest this is quite interesting and mystifying although I know that that sentiment does not help per se. So please do not be offended if I unintentionally insult your intelligence. Working "remotely" is always a bit awkward.

I sort of wondered about "new home" with the thought that maybe some other device was left in the system. Discounted that for two reasons: it all worked for a month and the fact that only wired (physically connected devices) are somehow ending up with 196.168.0.x addresses.

And I am not having any luck reverse engineering the process. As if I wanted to make a loss of network connectivity change the wired address IPs from 10.0.0.x to 192.168.0.x happen.

But I would like to see if it can be blocked from happening. One way to do that is to assign static 10.0.0.x IP addresses to the desktops based on their MACs. (I.e., reserved IPs.) Just use IP addresses outside of the range used for DHCP IP assignments. Maybe just test on one desktop to begin with.

Sharing the suspicion the modem/router is the culprit - maybe a bad or incorrect firmware update was pushed. But two modems.....?

And the more details and circumstances you can discover may help some other forum member to spot what I am missing.

 

[Romney]

I was going to save the ipconfig/all but my husband closed it before I was able to save it. If it happens again, I will definitely save it and share it. So, I'm thinking about setting up the reserved IP addresses. But I think I want to try to get it to happen again to get more data.
It's very random when it happens. It appears to happen when we lose connectivity to Comcast for some reason. Not like power outage, but actually, Comcast service outage?

 

[Ralston18]

Thanks. Just capture the information as time and circumstances warrant.

There could be a relationship to the Comcast outage but I find myself unable to even hazard a specific guess or two.

The primary reason being that wireless connectivity is not affected whereas wired conectivity is affected.

It is almost as if the wired devices are finding another DHCP router and getting their IP's assigned accordingly. That would make the wired adapter settings suspect on all three desktops. Plus that also begs the question of where is the "router".

That is why I am interesting in seeing the full adapter configurations via "ipconfig /all".

And as another line of thought: Have you traced the related wiring in your new home: i.e., looked for any miscellaneous boxes or devices left somewhere in the wiring path? Maybe by some other ISP or telephone service? Does the alarm system provide any indications of problems or failure?

Any splitters outside of your home connected to wires going to places unknown? Or wires coming in from places unknown?
======

Edit/Question: Are you comfortable with regedit? My thought is to conduct a search of the registry for 192.168.0.x on the applicable desktop. Just to determine "if and where" that IP address appears. As always back up the registry first and take your time during the search. Theoretically, that address should not be in the registry or, if it is, there should be some plausible explanation accordingly. Did not find any unexplainable occurences in my registry.

Also noted that, per your user manual, the setup offers three subnet masks: 255.255.255.0 and two others that I cannot see. What are the other two subnet mask choices please?
=======

In the meantime I keep hoping that someone else will toss in an idea or two....

Also: I am interested in the results from arp -a via Powershell....

Ref: http://tomoconnor.eu/blogish/how-to-find-rogue-dhcp-server-your-network/

 

[Romney]

So, just as an update, I set all of my devices to static IP addresses within the router and stopped having problems. I started looking around my network afterwards trying to figure out what might have been causing the problem. The only thing I could come up with was the Wink Hub was acting as a rogue DHCP... I was able to find this thread on Reddit to support my theory. Currently, my wink is unplugged and I'm not having any more issues.

https://www.reddit.com/r/winkhub/comments/3mxiuv/wink_hub_has_rogue_dhcp_server/

Thanks again for all of your troubleshooting advice and help Ralston!

 

[garrixmartin048]

I recently moved to a new home and needed phone service for my alarm system. So I ditched my Motorola modem to use the Xfinity Wireless Gateway.
After about a month of use, we had a this problem with the modem.
We have 3 desktop computers that are hardwired to the modem and about 5-7 devices that connect wireless.
The modem went offline over night and when it came back up, none of the desktops would connect to the internet. Windows displayed unidentified network -no internet access.
Power cycled the modem, restarted the computers, still not getting connected.
replaced Ethernet cables and checked the IP address.
All of the desktops were getting IP addresses in the range of 192.168.0.x
Now, I know the IP address range of the gateway is 10.0.0.x, so these addresses made no sense to me at all. So I called Comcast for support. I was unable to get anyone to understand the problem I was having. The rep on the phone told me he would escalate the call to tier 2 but it could be 24-48 hours before someone could back to us.
So, instead of waiting, I decided to reset the modem to the factory default settings and start over.
Once I reset the modem, It took a while but we were able to go back through the set up process of set the networks back up. And everything started working again.
Later the next day, the tier 2 person called and said they fixed it. I said no, you didn't fix it, I did, I reset the modem to the factory default settings. We continued to argue for more than 30 minutes and she ended up hanging up on me because I told her she wasn't listening to me.
So, since, this has happened 4 times. on time number 3, I asked to have a tech come out and replace my modem. Of course, the tech didn't understand the networking problem that was occurring, and just replaced my modem. And it started happening again.
So, resetting the modem to the factory default settings corrects the problem but every time I do that, I have to reconfigure all of the smart devices I have connected to this POS modem/router.
And it becomes a huge hassle.
This issue really makes NO sense to me at all.
At the time the issues first started, 2 desktops were running windows 7, the other Windows 8.1. After we replaced the modem, we upgraded all three of the desktop computers. Replaced 2 MB's and processors. All are now running Windows 10.
We aren't running a 2nd router. We don't have a range extender. We don't have a DHCP server running on any of our computers.
And still, occasionally, we are getting incorrect IP addressing being distributed to our desktop computers only.
While all of this is going on, our wireless devices are working fine.
I believe its a firmware problem with the Comcast Gateway. But I'm reaching out to the community for help. Is there anything else that could be causing this problem?
Any help would be appreciated!

Thank you,
Romney

Won't flushins the dns help here. Just open cmd and type in the command ipconfig /flushdns. It works in most of the cases.

PS: I found a guide which discusses this same problem. Also the solution for IP address problem with Comcast Wireless Gateway is here: 10-0-0-0-1.org