Night Hawk CM1200 Downstream Blinking

[ronmax999]

Off and on my downstream led starts blinking and I loose my internet.  I have seen some previous posts but I though I would post my connection.  Looks like 24 is an issue.  Any guidance is appreciated.

[FURRYe38 · Accepted solution]

Have the ISP take a look at the information I pointed too. 

[FURRYe38]

Power is too LOW and you have a ton of correctables and un-correctables that should be zeros.

https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

Please post a copy and paste of the modems event log page.
https://kb.netgear.com/30008/How-do-I-view-or-clear-the-event-logs-on-my-NETGEAR-cable-modem-or-mode...

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. 
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
Be sure to power OFF the modem for 1 minute then back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...

[ronmax999]

This has been going on for weeks but today it is horrible.  However, Comcast just informed me that they are working on a outage in my area.  So when it gets resolved I will clear the logs and get some fresh info.  thanks for the help

[FURRYe38]

Ok. Most of the time it's an ISP issue. 

Let us know how it goes after they complete there work. 

[ronmax999]

After the  outage yesterday, today I started losing my downstream at times again.  My work computer uses a VPN.  When I finally got hold of a Comcast agent and going through all the reboots they blamed it on my VPN.  So I said I will disable the VPN this weekend and if it fails then send an tech out.  Here are my current logs.  what do you think.

[FURRYe38]

Power levels are out of spec and way TOO LOW:

https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

ISP needs to raise the power here.

I see lots of correctables and UN-Correctables that should be zeros accross all channels.

Lots of criticals as well. Any Criticals, Errors or Warnings seen in the event logs needs to be reviewed and resolved by the ISP. Indicates a signal issue on the ISP line up to the modem.

Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 
What is the brand and model of the host wifi router connected to the modem?

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. 
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
Be sure to power OFF the modem for 1 minute then back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html
https://highspeed.tips/docsis-events/

[ronmax999]

Thanks for the reply.  The coax to the modem appears to be straight from the pole to the modem.  I have the VPN disconnected and the errors have stopped and the download led has been solid.  However, the power levels may have something to do with that.  I will update this link with any new info.

[FURRYe38 · Accepted solution]

Have the ISP take a look at the information I pointed too. 

[ronmax999]

I finally got a Comcast tech here that knew what he was doing.  He put in a ticket and they said that the issue has been resolved.  It looks like my power levers are much better and the TV has not paused since.  However, I am still seeing uncorrectable errors but no Critical events.  Is this normal or do I still have an issue??

[FURRYe38]

Yes power is good.

Have you power cycled the modem OFF for 1 minute then back ON or Factory reset the modem then wait about 5 minutes then take a new event log sample? 

[ronmax999]

I just had Comcast fix an issue where my power levels were -18 instead of -7 or greater.  However, I am still seeing uncorrectable errors in the thousands.  Is this normal or could the modem be going bad?  The pic below is right after I rebooted the modem.  Thanks for any insight.

[FURRYe38]

Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 
What is the brand and model of the host wifi router connected to the modem?

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. 
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
Be sure to power OFF the modem for 1 minute then back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html

Does the modem seem to be working better now?