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Re: CM1200 Loses Connection to ISP

dialup
Tutor

CM1200 Loses Connection to ISP

After about seven months of use, my CM1200 has started losing connection with my ISP(Comcast). This started three days ago.

At first, unplugging it would fix the issue, but within 24 hours I'd have no internet and Comcast wouldn't be able to connect to the device. It will at least sometimes reconnect at some point, though I can't be certain if it's ever happened without a power cycle being done at some point beforehand.

After getting home today, power cycling wasn't working, so I did a factory reset to no avail. Some minutes later while I was going through the support pages on my phone, I noticed my desktop regain connection out of the blue. 

My wife works from home, so this is having a major impact on us. 

 

Aggregation is disabled.

I have not tried having a computer directly connected for an extended period of time, but the fact that it worked fine for seven months and that Comcast can't connect to it when the issue is active points very strongly to early life failure of the device.

 

Hardware Version1.01
 
Firmware VersionV2.02.05
 
Cable Modem Serial Number 
 
CM CertificateInstalled
 
CM MAC 
Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
Message 1 of 8

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FURRYe38
Guru

Re: CM1200 Loses Connection to ISP

Have the ISP check the signal and line quality UP to the modem. 
Be sure to power OFF the modem for 1 minute them back ON.

View solution in original post

Message 4 of 8

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plemans
Guru

Re: CM1200 Loses Connection to ISP

Take a screen snip of the cable connections page/pages (all of it) and the logs. 

this helps check the signal back to the isp. 

If you have any splitters, amplifiers, or attenuators, I'd recommend removing them. 

Check the cable for kinks, damage, bad/cheap/loose connectors, etc.  

 

Message 2 of 8
dialup
Tutor

Re: CM1200 Loses Connection to ISP

Thanks for the reply.

Here's the table. The event log is empty, which seems odd to me.

Cables have been checked and reseated. No splitters or amplifiers.

We had a good connection at 6am, but it went bad sometime in the morning. Right now, it keeps going in and out, lasting for maybe a few minutes at a time.
Message 3 of 8
FURRYe38
Guru

Re: CM1200 Loses Connection to ISP

Have the ISP check the signal and line quality UP to the modem. 
Be sure to power OFF the modem for 1 minute them back ON.

Message 4 of 8
dialup
Tutor

Re: CM1200 Loses Connection to ISP

Comcast is sending a technician on the 24th. Whatever diagnostics they can run remotely didn't turn anything up.

 

Almost all of the modem reboots were power off, unplug, wait ~ a minute, plug in, power on. A couple of times it was left unplugged for several minutes.

Message 5 of 8
plemans
Guru

Re: CM1200 Loses Connection to ISP


@dialup wrote:
Thanks for the reply.

Here's the table. The event log is empty, which seems odd to me.

Cables have been checked and reseated. No splitters or amplifiers.

We had a good connection at 6am, but it went bad sometime in the morning. Right now, it keeps going in and out, lasting for maybe a few minutes at a time.

connections don't look bad other than the 1 upstream not locking. Usually its 1-2-3 or some version like that. Not skipping one. 

Also it is odd there isn't anything in the event log. 

Message 6 of 8
dialup
Tutor

Re: CM1200 Loses Connection to ISP

Well, it turns out that the coax coupler between cable coming into the house and the one going to the modem was the cause.

The tech also said that when he looked at our signal history, it had been problematic for some time. I don't know why it only became noticable this past weekend, or why Comcast wouldn't be proactive about this sort of thing if they're tracking it, but whatever.

 

The modem also decided to start actually keeping an event log this morning.

 

All's well that ends well, I suppose.

 

Thanks for the help.

Message 7 of 8
plemans
Guru

Re: CM1200 Loses Connection to ISP

Either way, glad to hear you got it fixed!

Message 8 of 8
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