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Aspirant
Posts: 5
Registered: ‎2012-02-25

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!
Luminary
Posts: 89,285
Registered: ‎2009-01-27

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

CMD31T is not listed under support.netgear.com then it will be ISP specific devices.

I have not seen any posting on this issues so I would suggest to go back to ISP and get unit exchange to different models is best options

when device is modem only then double would not come from this unit. your ISP may not given you the public IP (routable IP) there fore you may getting double NAT
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June Mizoguchi-
Aspirant
Posts: 5
Registered: ‎2012-02-25

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Isn't this the modem on support.netgear.com: http://support.netgear.com/app/products/model/a_id/19390
:confused:

I haven't read this issue anywhere either which is why I'm really confused. This modem is listed as a supported cable modem under Comcast so I don't why it shouldn't be work the way it should. I also bought this from Amazon (the first one was from TigerDirect) and not from Comcast. Do you mean to switch it out for a completely different model from a different brand or switch it out again for the same model? This is the second unit of the same model that I'm experiencing this issue.

Aside from the double NAT issue, how then would you explain the cable modem still dropping after connecting directly to my computer without any router in between?
Luminary
Posts: 89,285
Registered: ‎2009-01-27

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Aside from the double NAT issue, how then would you explain the cable modem still dropping after connecting directly to my computer without any router in between?



forum is not support so you will need to deal with support and possible get exchanged. like said, you will not find much of user of this model in forum so you will find less reply who may have this model to share unless you are willing to wait for a while ...

I'm comcast but I don't use this modem
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June Mizoguchi-
Luminary
Posts: 89,285
Registered: ‎2009-01-27

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

suggest to test out with different cable modem

I use to use dlink modem and never failed. I would try using model that comast usually supply to customers.

My area, I never seen this model supplied. dlink was also not used with comcast but I had good luck with..
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June Mizoguchi-
Aspirant
Posts: 5
Registered: ‎2012-02-25

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

So the solution is: don't buy a Netgear cable modem, even though I'm asking on the official Netgear forums. Smiley Sad

It makes no sense, when the modem is listed as an officially supported cable modem under Comcast and that this model still is currently in production and is still selling. Why?

It says it right here: http://mydeviceinfo.comcast.net/

It also has the same 1 out of 3 star Comcast certification as my current leased cable modem so its on the same level.

This is extremely frustrating.
Luminary
Posts: 89,285
Registered: ‎2009-01-27

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

even though I'm asking on the official Netgear forums


Like said, this not netgear support forum. forum is user to user ONLY


I would talk to comcast support. Haven then come out and test lines and etc.
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June Mizoguchi-
Aspirant
Posts: 5
Registered: ‎2012-02-25

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Just contacted Netgear support and they said that Comcast would have to support me directly just like you said. They said that Comcast engineers would have to flash certain firmware specific to their service. Called Comcast and they said nothing like that needed to be done.

Anyway thanks for the help. Looks like this product is just a dud and I'll be returning it.
Aspirant
Posts: 3
Registered: ‎2012-02-25

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

I have one of these and it has failed. Netgear is clueless. Good luck.
Highlighted
Aspirant
Posts: 3
Registered: ‎2012-02-25

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Netgear is full of sh!t! I own one of these and it has failed.

Netgear tried to give me the same BS about calling Comcast. This is a privately purchased modem. Comcast has NO responsibility to provide ANY support! Netgear wants to avoid supporting their own faulty products. I'm trying to get an RMA and Netgear is doing everything possible to refuse.

It looks like I will have to write a letter to my Attorney General.
Aspirant
Posts: 5
Registered: ‎2012-02-25

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Yea, I agree. I'm through with Netgear. There technical support responses over the phone seemed just like a lot of BS. Comcast had no idea what I was saying when I told them that Netgear said that Comcast engineers had to flash specific firmware/software on to their modems for their customers. This modem should be black listed from their approved modem list. After two units and faulty performance, this product is a scam.

Good luck on the RMA. Hope you get your money back. Netgear's customer service is pretty horrendous.
Novice
Posts: 0
Registered: ‎2011-12-04

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

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?
Tutor
Posts: 81
Registered: ‎2012-06-21

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Hi,

Can you tell me what is the LED behavior of the device when it disconnects you from the Internet.
Aspirant
Posts: 2
Registered: ‎2012-03-19

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

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.
Luminary
Posts: 89,285
Registered: ‎2009-01-27

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

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
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June Mizoguchi-
Aspirant
Posts: 2
Registered: ‎2012-03-19

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

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.
Aspirant
Posts: 4
Registered: ‎2012-03-25

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

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.
Tutor
Posts: 144
Registered: ‎2011-05-11

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

knwn issue, netgear is working on it
Tutor
Posts: 144
Registered: ‎2011-05-11

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

issue has been resolved with comcast, ur device should work fine now
Aspirant
Posts: 4
Registered: ‎2012-03-25

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

I disagree IDXPIRED.... I have been getting dropped every 15 min. Been on since 7am PST.
Aspirant
Posts: 2
Registered: ‎2012-03-31

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

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.
Aspirant
Posts: 3
Registered: ‎2012-08-13

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

I just bought this device from a Charter authorized dealer in March. At that time this device was approved to be on the Charter network. It has since been blacklisted and I was told I needed to address this with Netgear.

I found the blog discussing this Netgear CMD31T http://forum1.netgear.com/showthread.php?t=75134 and the article regarding problems with Comcast.

Just got off the phone with Netgear "support" regarding their being blacklisted from Charter. The tech told me first that this was Charter's problem but they could help getting connected to the network maybe. She was an idiot. Did not compute through her brain that they were blacklisted due to incompatibility. She said it must be Charter's fault because their device shows compatibility and they haven't heard of any issues. The tech said she was going to call Charter - then called me back to say she couldn't find their phone number. I swear.:confused:

As it turns out I am connected (although I experience issues) because I connected during the time they were still authorized. Being blacklisted means Charter can kick me off at any time and if I get off their network cannot ever reconnect with this device.

Netgear needs to issue a firmware update or a new modem and replace this one at their expense.

What they are doing at Netgear is fraud plain and simple. They continue to sell a product that not only does not work with specified providers but one that they are blacklisted from. Time to contact the AG, BBB, FTC and others.
Aspirant
Posts: 1
Registered: ‎2012-08-15

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Hello all - I joined so I could post here of my similar troubles now with the CMD31T.

Our previous networking setup was experiencing service interruptions and our ISP said it was due to the device not accepting the firmware updates. This causes the modem to cycle (connection interrupt). On the advice of ISP, we 'upgraded' to a DCOSIS 3 modem - the CMD31T which was listed as compatable. We purchased in late March the device and online with it sometime in April. We immediately noticed improvement in multiple connection scenarios and were pleased - very much so.

Now we have the same problem as before and our ISP is telling us we should eith buy or rent more equipment. This is unacceptable - the device is less than 6 months old.

Someone needs to own this issue, and seeing that the same issue is seen at more than one ISP, then my feeling is that Netgear needs to own it, or ISP's need to figure out how to properly write firmware...

For two days now, I have tried to submit support ticket to Netgear and a message of 'We are unable to process your request due to technical problems' or similar wording appears each time. I am not here for support, so please don't try to redirect me. I am here voicing my concern of an issue that I, like others are having with a specific Netgear product.

Heaven forbid we could get a straight answer from someone.

Firmware updates are pushed from the ISP's for cable modems and a post on another thread of this same modem, the poster seems to indicate that firmware updates are different if the device is branded vs customer owned.

Is this correct? Please provide proof if true.

I've used Netgear for years with few problems and enjoy the ease, simplicity, and reliability of their products - until recently. I wonder how many of these units have been sold, because it seems the wheels are coming off the cart with this device and I find a less than 6 month life in the field to be unacceptable. Escalation seems to be the order here.
Luminary
Posts: 89,285
Registered: ‎2009-01-27

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Some these units sold in retail based in region which are for it's ISP and branded firmware loaded is correct.

If you have issues at portal my.netgear.com then try later day
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June Mizoguchi-
Aspirant
Posts: 3
Registered: ‎2012-08-13

Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Knock knock. Netgear has been BLACKLISTED from Charter. Again this means that NO NETGEAR modems are allowed to be connected going forward as of May 2012. Yet they as you can see are pretending this unit still can be sold for Charter. Fraud! I contacted the BBB and got a ridiculous letter back from a customer "support" rep asking for my help in researching how they were blacklisted and how they just never knew. Didn't offer me any solution. This is beyond outrageous. This is their business to know and to determine how to resolve it. They need to refund me for the unit and the cost of having a tech come out for an install with a different company's model. :mad:Next step Attorney General of CA office.
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