CM1200 speed issues

[AdeptMaven]

I just set up a Netgear CM1200 modem and a Netgear RAX 120 Router four days ago. I have Comcast gigabit service (speeds up to a gigabit download, 35Mbs upload) and link aggregation between the two services. For the most part it has been fantastic however once a day I have to reboot the modem because the speed just becomes unexplaininably slow. I use the nighthawk app to do a speed test to see what speed the router is recieving and it is receiving a download speed of about 30Mb/s and an upload speed of 20-25Mb/s. I reboot the modem and once it comes back online the speeds return to normal (the nighthawk app measures 1.1Gbs down and around 40Mbs up). Ideally a modem should never need to be rebooted (minus firmware upgrades). Do i have a defective unit? Is it a firmware issue? (i checked and the modem is runing the latest comcast approved firmware 1.02.02). Has anyone experienced anything similar? Any help is much appreciated. 

[Huskuldar]

I have the exact same issues with the exact same equipment. Narrowed it down to the RAX120. Going to do a pin hole reset, wait 10 minutes and download new firmware. It's annoying as hell and does not seem to be the cable modem. I went back to the previous firmware without armor as I thought armor was the problem, it's not.

[AdeptMaven]

So did some more digging and found a thread thats several months old but it appears the issue is Link aggregation and NetGear does not have a fix yet. 😞

https://community.netgear.com/t5/Cable-Modems-Routers/CM1200-slows-down-after-24-48-hours-of-uptime-...

[Huskuldar]

Ok, Thanks! Disabled it on both.

[Topology]

AdeptMaven and Huskuldar, to clarify, you are observing the link aggregation performance problem when using the new RAX120 firmware 1.0.1.122 (together with CM1200 1.02.02 on Xfinity 1000Mbps service) - correct?

In addition, I am curious:  have you enabled IPv6 on the RAX120?

Thank you.

[AdeptMaven]

At the time I did not have ipv6 enabled. I have since enabled ipv6 but have disabled link aggregation. Should I try link aggregation with ipv6 enabled? Does that fix the issue?

[Huskuldar]

Yes, most current firmware, Xfinity 1gb service, IPV6 is enabled, link agregation disabled. After disabling link agregation service has been perfect.