CM1000v2 cannot access 192.168.100.1

[rkalinka]

How many times did you have to perform the factory reset?  I am having the same problem - performed a factory reset as specified in the note - no change in behavior.

[Kitsap · Accepted solution]

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@rkalinka wrote:

@Kitsap - I don't think my Netgear modem has those configurations available to it as it's only a Modem (not a router).  When I get a minute do more testing on my environment, I'll see if there is a way to drop in a static route on the MODEM (but I don't think so). 

That being said, I could always try to put the static route you mentioned on my ROUTER to see if that fixes the issue - certainly a good idea.  That being said, I was having the same URL failure problem when I hooked up my laptop directly to the modem (bypassing the router completely) so I doubt putting a static router on my ROUTER will fix it.... but, I will chase this down as anything is possible and I would like to get it working again.

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@rkalinka 

The static route for access to your modem is a configuration you apply to the router.

[rkalinka]

Having the exact same issue... did you every get a resolution?

[plemans]

@rkalinka have you started your own thread? 

Try doing that. 

Go over your full setup, what you've tried, and what results your getting

[rkalinka]

Hoping someone may know why all of a sudden, I can't access the CM1000v2 modem diagnostics page: http://192.168.100.1 It boots up and seemingly resets its settings, reconnects, but still doesn't let me in.  I have no problem with internet access, but I cannot access the modem configuration page at 192.168.100.1.

It won't load the login screen and only times out.

I performed a factory reset (while unplugging COAX) - same behavior.

I did another factory reset while is everything was plugged in - for a minute, I could get to the login screen, but when i plugged in my information (click login), it just refreshed the login screen again.
Another minute later, back to timeout errors.

To debug this. I've got my laptop (PC) connected to the modem directly (so there's no wifi/router concerns) and nothing else is connected to the modem.

When I try to access 192.168.100.1, the web page just times out without giving me a login prompt. I've rebooted the modem and laptop and tried a factory reset and nothing has made any difference.

What I have noticed is that when I first reboot the modem, my machine gets 192.168.100.10 as its IP address (but 192.168.100.1 doesn't respond at this time). Once the modem is fully booted and connected, my IP address flips to 73.223.xxx.xxx (Comcast public IP space).

Other things I've tried:

-Looking for 192.168.0.1, 192.168.1.1, 192.168.100.10 but none of those IPs respond either.
-Tried a different (Windows) laptop just in case there was something weird in the networking on my first laptop - same behavior.
-Tried reconnecting to my home network - same behavior (Network path is PC-->Asus RT-AC88U Mesh --> Netgear CM1000v2 --> Comcast Coax)
-Tried reconnecting to my home network via iPhone and iPad - same behavior (Network path is Apple device-->Asus RT-AC88U Mesh --> Netgear CM1000v2 --> Comcast Coax)

NOTE - this issue only started after a RECENT comcast outage in my area that has since been resolved. Prior to this outage, everything worked as expected. As mentioned, I can get to the internet, so it's not the end of the world, but I simply cannot login to the modem to check status.

Thanks in advance!

Rob

[tmbrwolf]

When I had this problem (my post from a couple years ago), I recall only needing to reset it once with the coax disconnected. I can't check right now, but I was still able to access the settings page a few months ago.

[rkalinka]

THe odd thing is that I am able to login for about 3 seconds to see that it connected to Comcast  but as soon as i get the comcast IP assingned to it, the Netgear UI no longer responds.  It's almost as if the internal website is getting redirected somehow, but all requests to the webUI simply timeout.

[plemans]

Can you ping 192.168.100.1?

Did you try a different web browser?

[rkalinka]

I cannot ping the address from anywhere.  I get the same behavior from Edge/Chrome/Firefox.  (I primarily use Chrome for this type of stuff)

[plemans]

are you using any vpn's, security suites, dns managers?

[rkalinka]

On my router - It comes with Trend Micro protection - i checked there for any blockers and see none.  I am using Google DNS (servers) on my router (not the default Xfinity ones since they are not reliable).  While there is VPN support here, I don't have it enabled or configured here.  Doubt any of this would matter as i have the same behavior when I plug in a PC directly into the modem (bypassing the router all together).  There is no additional DNS manager.

On my PC's - They have the same software install - win10, McAfee endpoint protection, Cyberreason Antivirus, Cisco VPN.  For my tests, I do NOT enable VPN.  I have checked the logs on both McAfee EPP and Cybereason with no mention of blockers.  NOTE - given that i can see the Netgear UI for a few seconds when it's NOT connected to the internet, I don't believe the issue resides here.  Showing google DNS as designed.  There is no additional DNS manager.

On my iPhone/iPad - latest versions of iOS. no VPN  using Google DNS - There is no additional DNS manager.

If it matters, my Xfinity plan is 600MB down and 25MB up.

[plemans]

any stock computers without protections/vpn's built in you could test with? 

Seems odd that it works until its online. That's what makes me suspect something on the pc/devices are going point to point encryption/tunneling. If your devices are iOS/mac, make sure icloud relay and private mac/ip address are disabled. 

[rkalinka]

I have tried with another Desktop - Win10 - Windows defender is on it, no vpn or EPP.  Same behavior.

I have tried with my iPad - disable private IP -- (iCloud private relay was not enabled) - same behavior.

It's almost as if the embedded web service changes IP address or something.

[plemans]

But everything is still working well? 

Not sure why you can't access it. 

If you disconnect the coax and reboot it, are you able to log into it with it disconnected?

[rkalinka]

Yes - that is the odd part.  My service seems to be performant and working as expected as per my plan bandwidth.  I simply cannot see what is going on in the modem if there are any errors or whatnot.  While I don't check the devices every day, part of the reason for getting away from Comcast supplied equipment was so that I can see what is going on when there are issues (which is simply not possible with Comcast devices and support - no matter whom you talk to there).

We are working from home today, so I will test one more time what you have asked when I can get a break.  BUT - when I performed a reboot yesterday (with unplugged coax), I was able to login and see "not connected".  I then screwed the COAX back on and waited a little bit for the modem to join Comcast network again - I refreshed the Netgear UI page - it showed connected.  About 3-5 seconds "after" it's connected - all attempts to navigate the UI and/or login to 192.168.100.1 timeout and I can no longer see that admin page no matter what I try.

I'll post back here with updates  - hopefully within the next couple of hours if I can, otherwise it'll have to wait until tonight when nobody else is on.

[rkalinka]

UPDATE: With everything "working' aside from the netgear UI, I unplugged the COAX only and waited a few minutes.  Obviously, I lost my internet connection, but aside from that, I still could NOT get to the Netgear UI.

The next thing I did was reboot the modem (COAX unplugged) - the modem responds and works well on 192.168.100.1 - and shows "cable connection down".  I left it like this for about 5 minutes - no issues getting in and out of the modem.

I plug in the modem to COAX - the WebUI shows "cable connected" for a couple seconds then it timesout, i see the ip flips to 192.168.100.10 for a couple seconds, then to a 75.x.x.x IP.  I still cannot login to the Netgear modem but my internet service is running fine.

I have got to believe the webUI changes name resolution to some Comcast IP, but i have no way of knowing what it is.  And i have got to believe it's feeding information to Comcast via that IP address.

[Kitsap]

You may think your internet service is running fine, but your computer is directly exposed to the internet with no firewall.  Not a good situation for browsing the internet, accessing e-mail, banking, etc.  Your computer is using the Domain Name Servers (DNS) direct from your internet provider to access web pages.

Power down your modem, router, and computer and disconnect the coax from the modem.  Connect port 1 of the modem to your router WAN port with an Ethernet cable, connect your computer to a router LAN port with an Ethernet cable.  Leave your other hardware disconnected.

Connect the coax to the modem and power up the modem.  Give it plenty of time to fully boot and make connections with your internet service provider.  Power up your router and give it plenty of time to fully boot.  Power up your computer and give it plenty of time to fully boot and obtain an IP address from your router.

Log in to the GUI console of your router.  Verify the IP address of the router is 192.168.1.1.  If it is not, change the address in the LAN TCP/IP setup and restart your router.  Verify the date time on the router is correct.  If not, check your NTP settings.  Your router should be configured to dynamically get an (external ) IP address from your ISP.  You should see the 75.x.x.x IP you mentioned above.

Access to your modem GUI console is dependent on their being a local area network configured and running.  With no router connected, you do not have a LAN.  Your modem IP address, 192.168.100.1 should be on the label on the bottom.

In your router configuration, you have an option to choose a different IP address. I chose 10.0.0.1.

As many times as you have tried this and not been successful you may have to clear the cache on your web browser.  I have a CM2050V and can access the 192.168.100.1 address using either Firefox or Edge in Windows 10.  The router in between the two is a Netgear R7800 with a set IP address of 10.0.0.1.

[rkalinka]

@Kitsap - Thanks for the additional info.  I guess I should've been more clear.  I didn't leave my Laptop hooked directly into the modem for long - I was only doing that for triage to confirm my router wasn't blocking it somehow.  My steady state network leverages my router (with firewall) - so I didn't bypass my home security for long.

That being said, my router doesn't appear to be the issue here - it's separate from the netgear modem and I can see everything on it.  I have full control over my network in this regard and can set it to whatever I want much like yourself.  Oddly enough though, I see the same behavior from my router's Public Internet IP address as I do when i tried my laptop (when it's hooked in directly) - the modem starts with 192.168.100.1 - then it flips to 192.168.100.10 (for a second) then it flips one more time to the 75.x.x.x IP from comcast and then I can no longer get into the Modem UI at 192.168.100.1 even though I have internet service.  As far as I know, the modem has no security on it whatsoever (beyond admin password that I did change away from default by the way) - so I agree, hooking directly into it is no bueno even though I do have a firewall on this machine as well.  (I checked my local logs as well with no blockers showing.)

I have cleared cache and tried different browsers on multiple windows machines as well as iPad/iPhone - which is why I tried bypassing my router (temporarily as well). When the modem COAX is disconnected, I can login to it on 192.168.100.1 - with no issues - and for a long time - the UI is fairly responsive, and I can get to all the modem settings when it's in this state.  I also looked for some ebedded website configs options to see if some sort of DNS redirect option existed and was enabled - but I don't see anything.  As soon as I plug the COAX back into the modem - the ip's flip (as describe above), and then I can no longer get into the modem.  This behavior happens whether i go direct to the modem (temporarily) or through my usual router/network config.

Prior to the recent Comcast outage in my area, I was able to see the netgear Modem just fine from my home network so I am not really sure what changed.

If it matters - my home network is 192.168.1.x (with the router being 192.168.1.1) - but this shouldn't really matter as it all communicated correctly.  As I understand it, even though I configured Google DNS servers on my router, Comcast will ultimately route it back to their DNS when packets leave my network.  They do some goofy things with "shaping their traffic" on the back end that nobody in Xfinity support would truly explain.  For giggles, I did try reverting my DNS servers to the Xfinity ones - with no change in behavior.

[Kitsap]

This is a good modem firmware address for reference: 

https://kb.netgear.com/000036375/What-s-the-latest-firmware-version-of-my-NETGEAR-cable-modem-or-mod... 

Strange behavior with your setup.  I helped a friend commission a CM1200 a few weeks ago on Comcast and all works well and as expected there.

[Kitsap]

@rkalinka 

Additional information.

From a Windows computer, as an administrator, use the Command Prompt or Power Shell to issue the command:  IPCONFIG /ALL.

The return information will show the IP v4 and v6 address of the computer, lease information, and the IP address of the gateway (should be your router).  It will also list DNS servers as your router.

Within the router configuration, I recommend you enable IPv6.  I am certain Comcast supports it across their network.

For DNS servers, I use a series of Open DNS, Comcast, and Next DNS.  These work well for my location.  See attached snips.

[morlan52]

@rkalinka did you ever figure out a resolution to this issue? I'm having this exact same issue. Can reboot the modem without the coax plugged in and can access the web configuration interface, but once I connect that cable and internet access is restored I can no longer access and/or ping. 

I'm also on Comcast/Xfinity. My internet connection and bandwidth are working as expected otherwise, however I have been having intermittent internet drop issues over the past week and looked further into the modem where I discovered this issue. I suspect that the modem may be having internal issues.

Thanks!

[Kitsap]

@morlan52,

Setting up a static route within your router has helped some overcome this situation. 

See attached.

[rkalinka]

@morlan52 - I never got this figured out.  I had gone round and round with Netgear and Xfinity support with no answer.  Netgear indicated that it's something that Xfinity does since THEY are the ones who push firmware updates (and not Netgear).  Xfinity has no idea what Netgear is talking about - and you can't get to anyone in Xfinity who has any real technical knowledge to be able to fix the problem. So  - i could either PAY for technical support (to still have no answer), or just go purchase another modem at that point.

All in all the modem DOES work and my service is as expected.  For the issues you are talking about, I looked on my own home Router (not netgear) for issues and messages (I had a couple gremlins on my network before that I was able to track down.).  IE - it usually shows something if there are problems with the ISP not working for a given timeframe as well.  So - I just rolled forward with my config while it's all working.

From the Xfinity side of things, the best they can do is run a signal check as well as run a line check - if both of those are OK, then there's nothing Xfinity will really do.

If you find a fix, please let me know!

[rkalinka]

@Kitsap - I don't think my Netgear modem has those configurations available to it as it's only a Modem (not a router).  When I get a minute do more testing on my environment, I'll see if there is a way to drop in a static route on the MODEM (but I don't think so). 

That being said, I could always try to put the static route you mentioned on my ROUTER to see if that fixes the issue - certainly a good idea.  That being said, I was having the same URL failure problem when I hooked up my laptop directly to the modem (bypassing the router completely) so I doubt putting a static router on my ROUTER will fix it.... but, I will chase this down as anything is possible and I would like to get it working again.

[morlan52]

@Kitsap and @rkalinka thank you very much for your replies. Adding a static route for this in the router did end up resolving my issue. Interesting, because this was not previously required before for me to access the modem page. Something must have changed recently on Xfinity's end perhaps. 

Should be more able to resolve my intermittent internet issues now more easily with visibility into the modem - thank you again.

[Kitsap · Accepted solution]

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@rkalinka wrote:

@Kitsap - I don't think my Netgear modem has those configurations available to it as it's only a Modem (not a router).  When I get a minute do more testing on my environment, I'll see if there is a way to drop in a static route on the MODEM (but I don't think so). 

That being said, I could always try to put the static route you mentioned on my ROUTER to see if that fixes the issue - certainly a good idea.  That being said, I was having the same URL failure problem when I hooked up my laptop directly to the modem (bypassing the router completely) so I doubt putting a static router on my ROUTER will fix it.... but, I will chase this down as anything is possible and I would like to get it working again.

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@rkalinka 

The static route for access to your modem is a configuration you apply to the router.