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Re: CM500 Modem keeps dropping internet, then reconnecting eventually

ragerDuane
Guide

CM500 Modem keeps dropping internet, then reconnecting eventually

I used to use my CM500 modem with R6700v3 router with Vyve Broadband at my old address. I never had any significant internet issues. I moved to a new location and got service with Sparklight. Everything was fine for the first 3 days. On the 4th day, my internet just started dropping for several minutes, and then reconnecting. This has gone intermittently all day. This happened simulataneously with wifi and ethernet. I later plugged my computer in directly to my router and the issue continued, confirming that it is not the router or anything wired after the modem. I physically checked all wires from the wall out and found no loose connections or damaged wires. I also tried resetting the modem, my router, and computer. I tried a full power cycle, too.

 

I called Sparklight. They saw live, the same time as me, when my modem would disconnect and then eventually reconnect. They supposedly didn't see anything on their side that could resolve the issue. They are sending a technician to come look at the lines outside, but already warned me that if they find nothing they are going to ask me a to use their modem. If I decline that, they will tell me to get a new modem. I don't think I need a new modem. It worked perfectly with my last ISP, and it is barely 1 year old. They, of course, did not even ask about my modem's reported cable connection or event log. I am skeptical that the technician will either.

 

The one thing on my end that I can think of that POSSIBLY is the issue, is that I moved my desk a couple days ago and when I put it back I pushed it up against the coax cable. But it has been like that for a couple days and the issue just started today. I don't think it was hard enough to crush or bend it. Also, I pulled the desk away, and upon visual inspection, there does not seem to be any physical abnormality. I will switch that cord out before trying a new modem, but in case that is not it, I still want to be prepared to face the ISP when they blame my modem.

 

I will post my cable connections and event log, as well as another event log right after a power cycle.

 

What do you guys think the issue is?

Model: CM500|16x4 DOCSIS 3.0 Cable Modem
Message 1 of 10

Accepted Solutions
plemans
Guru

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Check you line for amplifiers, attenuators, or splitters. remove them if you have them. check the line for damage, kinks, cheap/old/bad/loose connectors. 

Reason is your power levels are out of spec. They're to low and they should only be 3.5dbmv from each other. You're going from -11.2 dbmv (with errors) to -0.1dbmv.  so 11.1dbmv difference. couple that with the logs and theres issues with the line. 

 

if you checking your side of things doesnt help, then the isp needs to check that. 

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Message 7 of 10

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ragerDuane
Guide

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Here is the event log.

Model: CM500|16x4 DOCSIS 3.0 Cable Modem
Message 2 of 10
ragerDuane
Guide

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Here is the post-power cycle event log.

Model: CM500|16x4 DOCSIS 3.0 Cable Modem
Message 3 of 10
FURRYe38
Guru

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Please post a copy and paste of the modems connection status page.

 

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 
Be sure to power OFF the modem for 1 minute them back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...

Message 4 of 10
ragerDuane
Guide

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Here is the connections file.

Model: CM500|16x4 DOCSIS 3.0 Cable Modem
Message 5 of 10
ragerDuane
Guide

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

I couldn't get a legible copy and paste, so a pdf of the connections is attached above.

Message 6 of 10
plemans
Guru

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Check you line for amplifiers, attenuators, or splitters. remove them if you have them. check the line for damage, kinks, cheap/old/bad/loose connectors. 

Reason is your power levels are out of spec. They're to low and they should only be 3.5dbmv from each other. You're going from -11.2 dbmv (with errors) to -0.1dbmv.  so 11.1dbmv difference. couple that with the logs and theres issues with the line. 

 

if you checking your side of things doesnt help, then the isp needs to check that. 

Message 7 of 10
ragerDuane
Guide

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Thank you for that information! I will do that and then follow up on here.

Message 8 of 10
ragerDuane
Guide

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Thank you! That solved it. The ISP came and found a splitter on the outside of the house. They also suspect that an old cable could be damaged because it was run on top of the roof, fully exposed to all the elements for who knows how long. Cable connection looks great now, I have attached it to this post for reference.

Model: CM500|16x4 DOCSIS 3.0 Cable Modem
Message 9 of 10
plemans
Guru

Re: CM500 Modem keeps dropping internet, then reconnecting eventually

Much better looking connections page. Everything is within spec. 

Glad it took care of the issue!

Let us know if you have other problems. 

Message 10 of 10
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