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Forum Discussion
Brand new CMD31T Cable modem constantly dropping internet connection on Comcast
Hi everyone. This is my first post as I have a persistent ongoing issue with a brand new CMD31T cable modem. I'm actually on my second one as Netgear phone support told me that I had a defective unit. Anyway, this is whats happening...
Quite simply, the cable modem will continue to function perfectly (and very fast, I might add) for about 15 minutes, and then will all of a sudden drop internet connection. The lights on the modem go through the motions as if rebooting. The way I test when it drops out is I'll play some online games and wait for the cable modem to drop out, and it always does around every 15 minutes.
I have tried connecting to both directly to my Mac and to my Apple Time Capsule router and both yield the same results. When connected to the Time Capsule however, Airport Utility will display the error as a "Double NAT" error, but as I have learned, a double NAT means you have to routers conflicting with one another, and the CMD31T is strictly a cable modem with no router functionality.
I have contacted all three companies about this issue: Comcast, Netgear, and Apple. However this has nothing to do with Apple because as I've said, I have already tested the cable modem connected directly to the computer. Comcast already sent a technician when I had the first modem, and came up with the crazy logic that it was "old cabling" running through the house. After spending an hour replacing meters of cable, I tested the modem and it still dropped out. I never had this issue with my previous leased cable modem from Comcast so I have no idea why he thought it would be a wild coincidence that the cabling finally gave out just exactly the moment I switch cable modems out. I'm pretty annoyed by Comcast's competence thus far.
I'm equality frustrated and annoyed at Netgear, who told me that my unit was defective and that I should return it for another model. I'm now on my second modem, yet I'm still getting the same internet drop out and "double NAT" errors. Is there anyone that might know what is going on with this modem?? I really would like to like this modem but so far, it's been causing nothing but headaches for me.
I have read that updating the firmware might help, but I don't even know how to do that. I stumbled onto the Netgear modem setup page (http://192.168.100.1) but nowhere does it explain or link me to any firmware updates.
Any help on this issue would be greatly appreciated! Thank you!
Quite simply, the cable modem will continue to function perfectly (and very fast, I might add) for about 15 minutes, and then will all of a sudden drop internet connection. The lights on the modem go through the motions as if rebooting. The way I test when it drops out is I'll play some online games and wait for the cable modem to drop out, and it always does around every 15 minutes.
I have tried connecting to both directly to my Mac and to my Apple Time Capsule router and both yield the same results. When connected to the Time Capsule however, Airport Utility will display the error as a "Double NAT" error, but as I have learned, a double NAT means you have to routers conflicting with one another, and the CMD31T is strictly a cable modem with no router functionality.
I have contacted all three companies about this issue: Comcast, Netgear, and Apple. However this has nothing to do with Apple because as I've said, I have already tested the cable modem connected directly to the computer. Comcast already sent a technician when I had the first modem, and came up with the crazy logic that it was "old cabling" running through the house. After spending an hour replacing meters of cable, I tested the modem and it still dropped out. I never had this issue with my previous leased cable modem from Comcast so I have no idea why he thought it would be a wild coincidence that the cabling finally gave out just exactly the moment I switch cable modems out. I'm pretty annoyed by Comcast's competence thus far.
I'm equality frustrated and annoyed at Netgear, who told me that my unit was defective and that I should return it for another model. I'm now on my second modem, yet I'm still getting the same internet drop out and "double NAT" errors. Is there anyone that might know what is going on with this modem?? I really would like to like this modem but so far, it's been causing nothing but headaches for me.
I have read that updating the firmware might help, but I don't even know how to do that. I stumbled onto the Netgear modem setup page (http://192.168.100.1) but nowhere does it explain or link me to any firmware updates.
Any help on this issue would be greatly appreciated! Thank you!
29 Replies
Icaras wrote: The lights on the modem go through the motions as if rebooting. The way I test when it drops out is I'll play some online games and wait for the cable modem to drop out, and it always does around every 15 minutes.
Could you please specify the LED patterns of the modem? Do you experience the same LED status when it's directly connected to your router or computer?- Hi,
Can you tell me what is the LED behavior of the device when it disconnects you from the Internet. - I too have this modem and just like everyone else my modem died within two months of using it. I believe i have found a major bug with the firmware.
If you log is as admin to 192.168.100.1 and look at the logs, my modem reports critical ntp errors. If I look at the configured date and time, it says 1970!
Unfortunately I cant access any settings to change this.
I really hate myself for buying a netgear product. - Most NTP is hard coded in the firmware to begin with
You get wring dates because if ntp server is down which is hard coded - I went to my local frys electronics tonight to return my modem. The rep said that during the past week, many people have been returning their netgear modem. He told me that a recent firmware update from Comcast doesn't work with the cmd31t.
Solution. Buy Motorola. - CMD31T Disconnection Issues.
My modem kept disconnecting and reconnecting after a couple days and I began to get frustrated. Then a day later I was finally cut off from the internet. The CMD31T kept cycling trying to establish a connection. I noticed that the UP and DOWN 1/2 would flash a couple times go solid then drop in an endless loop. I called Comcast and they told me they didn't know what the problem was nor were there any outages. They said I could have a technician come out and see what the problem was. I honestly felt that my brand new $90 Netgear modem couldn't be the problem so I requested a technician anyways. A technician costs $50 to come out if they can't find a problem on their end. The following day I just said screw it I'll cancel the technician coming out and I will go re-rent my modem (A $7 charge is cheaper than a $50 one to see if it was modem after all). Returning from the Comcast store with the rental modem... I prepare disconnect the CMD31T and see that it was CONNECTED! I get on my pc and try using the internet to find Comcast wants me to activate my modem again.
What I got out of this....
When Comcast added the modem to my account they must have provisioned my account with the new rental modem bumping any settings with the CMD31T. At this point I get really irritated and call up Comcast and explain what happened. The representative told me that they are aware of the problem with the NetGear CMD31T and don't have a fix for it. (Why didn't the first rep. not tell me this when I called?) She started to actually tell me that the IPV6 is not working correctly between their hardware and this particular cable modem. So at this point I am not quite sure who is to blame but I just wanted to share my experience before someone calls for a technician or save them trips thinking they have a faulty modem.
I figure by now Netgear and Comcast are just exchanging emails right now blaming each other. So If you experience this problem just call Comcast and tell them to re-provision your modem. - knwn issue, netgear is working on it
- issue has been resolved with comcast, ur device should work fine now
- I disagree IDXPIRED.... I have been getting dropped every 15 min. Been on since 7am PST.
- Im having this issue as well except with Cox. Over the course of a month, i have had new coax cable, the line on the wall replaced, and entire new line put into my apartment, different routers, and 2 modems of this model, still the same problem as you guys. I get disconnected like 20 times a day. Netgear support did absolutely nothing, you get foreign people who you can barely even understand.
