Netgear Nighthawk C7000v2 keeps dropping Internet

[Reaper1962]

My firmware is just above the one approved by by my ISP (Cox). 

My logs indicate that I am being attacked by the DNS servers being used by Cox.

How do I know this? I went to the command prompt and ran the command ipconfig /all.

It showed all my internet information including the DNS servers.

See Item 1 attached.

I checked the logs on my modem and it records each time the attack is logged in the description column, the time it occured, the targed and source.

See item 2.

I had a Cox technician come out twice, spoke with Cox on the phone an explained it to them. I have tried a different modem just like the one I had been using since I purchased it new. It worked great, good speed and good connections until about 2 months ago. There is no firmware update and Cox Says that my connection looks good on their end.

I have no other choice except to go with a newer modem that is supported by the manufacturer. If the new modem does not sole the issue, I will give Cox the oppertunity to address it further. If I get no satisfaction, it will be good by Cox after 25 years of being a customer.

So long Netgear!

[FURRYe38 · Accepted solution]

Your power levels are all over the place. All channel power should be with in 2-3dbm of each other and mostly power levels are a bit too low as well:

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

You have some channels with too much correctables. They should be mostly zero.

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...

Overall the ISP needs to look at all these items and get them corrected. 

[FURRYe38]

First off IPConfig /All only displays current networking adapter and configuration information on the PC your running that command ON. This doesn't trigger ANY DoS attacks. 

2ndly, the log only shows what the modem is blocking successfully. You need do do a WHOIS lookup and see where those WAN IP addresses are coming from. 

3rdly, how about posting the following so maybe we can help you narrow down what's going on? Please post a copy and paste of the modems connection status and event log page.
https://kb.netgear.com/30007/How-do-I-obtain-the-cable-connection-information-from-a-NETGEAR-cable-m...
https://kb.netgear.com/30008/How-do-I-view-or-clear-the-event-logs-on-my-NETGEAR-cable-modem-or-mode...

[Reaper1962]

I am not saying that ipconfig /all is causing a DOS attack. That was only to show which DNS servers were being automatically supplied by my ISP. The source in the logs are the same ones that the ipconfig/all show. I did use IP address look up and had the

following displayed.

[FURRYe38]

How about the other two items? 

Something to discuss with the ISP regarding the DoS entries. The modem is only reporting what is' blocking and designed to do here. 

[Reaper1962]

[FURRYe38]

Got the Cable Connection status page as well? Need that too. 

I see lots of Criticals and Warnings that the ISP needs to review and resolve. This is on them. 

Also please edit out any MAC addresses, CM addresses, WAN IP addresses or product serial numbers from pictures before posting in a public forum for security reasons. 

[Reaper1962]

[FURRYe38 · Accepted solution]

Your power levels are all over the place. All channel power should be with in 2-3dbm of each other and mostly power levels are a bit too low as well:

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

You have some channels with too much correctables. They should be mostly zero.

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...

Overall the ISP needs to look at all these items and get them corrected.