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Old February 25th, 2012, 02:04 PM
Icaras Icaras is offline
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Default 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!
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  #2  
Old February 25th, 2012, 02:09 PM
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jmizoguchi jmizoguchi is offline
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Default 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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Old February 25th, 2012, 02:22 PM
Icaras Icaras is offline
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Default 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/produ...del/a_id/19390


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?
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Old February 25th, 2012, 02:28 PM
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Default Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

Quote:
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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Old February 25th, 2012, 02:30 PM
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Default 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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Old February 25th, 2012, 03:20 PM
Icaras Icaras is offline
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Default 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.

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.
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Old February 25th, 2012, 03:47 PM
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Default Re: Brand new CMD31T Cable modem constantly dropping internet connection on Comcast

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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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Old February 25th, 2012, 03:51 PM
Icaras Icaras is offline
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Default 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.
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Old February 25th, 2012, 04:04 PM
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Default 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.
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Old February 25th, 2012, 04:11 PM
JohnJoseph JohnJoseph is offline
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Default 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.
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