If I hook up my CM1200 to my router (an Asus RT-AX88U) in Link Aggregation mode, it seems to be consistenly slow down to only around 66-ish% of the full connection speed after somewhere between 24 and 48 hours of uptime. The only thing which seems to fix this is rebooting the CM1200. Additionally, I've had it running for at least a week now with Link Aggregation disabled, and I'm not seeing any slowdown, so it would appear that Link Aggregation is related to the problem. The firmware of the CM1200 shows up as V1.01.02, for reference.

Here is the issue and fix. I have the same moden and the Nighthawk AX8 router. My modem was giving me speeds at the average 900's mb/sec and every 12hrs, the speeds would drop to 12mb/sec. I would the reset the modem and the speeds would increase to my 900's mb/sec speeds. I then tried aggregation and it worked for a couple of days my speeds stayed at 900's mb/sec without issue then it began to drop back to 12mb/sec. With the AX8, you can test speeds directly from the router/modem and then I would test the speeds on my Nvidia Shield and they would match. First, Comcast is pissed that you are using their modem for $13/month. Secondly, you will actually have to contact a technical support supervisor. So I decided to call XFINITY (Comcast) and raise hell. They first began to speak me me as I am an idiot and dont know anything. You will have to reiterate that the Nighthawk CM1200 is compatible to their network and is also listed on their website. They ask you speedtest questions and things. Then they will talk down to you. Log into your modem and tell them you can see the frequency and they are not what they should be. Now asked them to bump up your speeds and then lock in the modem. They will argue a bit but they have to do it. Once modem is locked in I. And speeds are bumped, you will not have to restart the modem every 12-24hrs. They are trying to force you to use their modem which then dictates the speeds your devices are allowed to get.P.S. I have a Galaxy S10 5g, and need to know how to configure the wifi settings to get almost gigabit speeds on 5Ghz. I can only get 325-450mb/sec, which I know the phone is capable of faster speeds

Since I originally posted about my CM1200 link aggregation performance degradation I have found that performance can be restored without a power cycle or modem reset. Performance can be restored by a link disable / enable. This can be done by disconnecting and reconnecting one of the Ethernet cables or by disabling and enabling one of the switch ports that the CM1200 is connected to. When I take either of these actions full performance is immediately available. Then after another two to four hour time period performance will again be severely degraded. Repeating the change of port state will again restore performance. The change of port state to restore performance can be done on either of the connected ports. From my testing a down/up of one of the connected ports has restored performance multiple times, but each time performance degrades after two to four hours. The only result of my testing that I did not expect was that when in degraded mode if I disabled one port and left it disabled, performance was restored to what one would expect in a non port aggregation mode. However, again after two to four hours performance degraded. I then had to down/up the port that was active to restore performance. In terms of degradation my download speeds drop from 1150 Megabits to 20 to 25 Megabits. My upload speeds drop from 40 Megabits to 20 to 25 Megabits. I have an open case with Netgear support on this problem.

I turned offanthonypants wrote:In case people are still looking for hard proof, I've taken the liberty of recording a video of my own experience in ownership of a CM1200. I'm using Comcast Xfinity in Portland, Oregon, my CM1200 is running firmware V1.02.02, and it's connected via 802.3ad (LACP) link aggregation to a Netgate SG-4860 running 2.4.4-RELEASE-p3. My current speed tier is 175/5, but I was paying for Gigabit internet shortly after moving into this apartment and was seeing the same symptoms everyone here's been reporting: after about 24 hours of uptime, bandwidth is throttled to around 20Mbps up/down. Prior to this weekend, I thought that reboots were the best way to get service back, but resetting one of the ports in the LAGG group on my pfSense appliance also works -- I'd like to thank everyone who suggested this. As you can see in this video, my modem's been online for around 5 days, and though it isn't shown, my pfSense appliance has been online for about 9 days. After bouncing one of the interfaces in the LAGG group, Comcast's own speed test (which you should assume is exaggerating the speed of my connection) reports that my speed increases ten-fold. The last interface reset I'd made to a port in the LAGG group was a little under an hour prior, so to put this another way: it takes less than one hour for speed to degrade by 90%. I believe the bandwidth degradation is caused by utilization, but whether that's raw packet throughput or connections being made, I couldn't tell you without more information, and modems are unfortunately locked down. After having made this post last year, I spent some time troubleshooting and working on scripting a method of cycling the LACP member ports on my Netgate appliance, but in the end I gave up and turned off link aggregation on the modem. However, this morning, I've just received firmware version V2.02.05 (which isn't even listed on Netgear's own documentation), and because there's zero chance of finding out from Comcast or Netgear if this firmware resolves the LACP issue, I'll have to perform some testing and report back.

Why are you asking? Do you have a fix to the link aggregation problem?

Yeah, no offense, I know you're just trying to potentially help, unless you got a fix what's the point? A lot of us have already given out information like this tons of time to no avail. If you've got a fix I'll spare the 3 minutes to gather that information; otherwise, you just passing this along to Netgear isn't going to do anything. We've all heard that response in here before. Sorry for being salty, but every single one of us in here put down the money to buy the most expensive Netgear modem for a reason and that sole purpose doesn't work.

CM1200 slows down after 24-48 hours of uptime when using link aggregation

150 Replies

ThePiston450
Tutor
Nov 24, 2019
Having the same problem here. Opened a support ticket when first purchased but got the run around from net gear blaming Comcast for the issue. I have the rax120 router with cm1150 modem with latest firmware on both. I can confirm same findings, modem reset fixes issue after 24 hours of speed decrease. I wish netgear would fix this issue. I can also see that single wan on gigabit shows download of 940 and wan aggregation brings it to 1190. So it does benefit the gigabit connection. Netgear, please fix. All my channels are locked and signals are perfect in cable modem GUI also.
- FURRYe38
  Guru - Experienced User
  Nov 25, 2019
  Please post in this thread for your model modem:
  https://community.netgear.com/t5/Cable-Modems-Routers/CM1150V-LACP-LAGG-Firmware-Issue-Comcast-V2-02-04-and-V2-02-03/td-p/1792853/jump-to/first-unread-message
  
  This issue only for the CM1200.
  ThePiston450 wrote:
  Having the same problem here. Opened a support ticket when first purchased but got the run around from net gear blaming Comcast for the issue. I have the rax120 router with cm1150 modem with latest firmware on both. I can confirm same findings, modem reset fixes issue after 24 hours of speed decrease. I wish netgear would fix this issue. I can also see that single wan on gigabit shows download of 940 and wan aggregation brings it to 1190. So it does benefit the gigabit connection. Netgear, please fix. All my channels are locked and signals are perfect in cable modem GUI also.
sterlingsanders
Guide
Dec 01, 2019
I have a NETGEAR CM1200 (firmware V1.02.02) modem, RAX200 (firmware V1.0.1.10_1.0.40) Router, Ubiquity US-XG-16 (firmware 4.0.69.10871) Managed Switch, Comcast Xfinity 1gbps in San Francisco, CA, and can confirm I also have this issue.

With LACP-IEEE 802.3ad enabled, I get between 980Mbps-1150Mbps for 12-18hrs, then speeds drop to 28Mbps-32Mbps.

I began hard rebooting my router when it first arrived, and I thought the problem was with Comcast until I got to this thread. I then disabled LACP, et voila, 850Mbps-960Mpbs without reboots every 12hrs.

Rather annoyed, as the one of the primary reasons for purchasing the CM1200 and the RAX200 was the touted agreggation, both for line saturation and redudancy. I would really appreciate a fix here NETGEAR.
- Blake2423
  Aspirant
  Dec 09, 2019
  I’m have the same issue. Bought the cm1200 and an ax8 router to leverage link aggregation to support future speed increases. Every 12-24hrs though speed drops to 25mbps. Really hoping there’s a fix for this soon.
  - FURRYe38
    Guru - Experienced User
    Dec 09, 2019
    If users don't want to wait for the ISP fix to come thru, users can try a CM1100. This model modem doesn't have this problem.
    Blake2423 wrote:
    I’m have the same issue. Bought the cm1200 and an ax8 router to leverage link aggregation to support future speed increases. Every 12-24hrs though speed drops to 25mbps. Really hoping there’s a fix for this soon.
blew88
Aspirant
Jan 12, 2020
CM1200 modem, AX12-RAX120 router, 1Gbps download Comcast Bay Area setup here. Having the same issues as everyone else with Link Aggregation Control Protocol. Hopeful that Netgear support is working on this and will provide a fix in firmware.
- L3XANDR0
  Aspirant
  Jan 12, 2020
  I upgraded to a WiFi 6 router with a 2.5 gbps port, and I am no longer seeing a slowdown. I wasn't using link aggregation. The router is the Asus Rapture AX11000.
- ray102382
  Aspirant
  Feb 13, 2020
  Still no luck? I dont want to have to replace the modem. But at this point its not worth holding out.
  - sterlingsanders
    Guide
    Feb 14, 2020
    Just disable link aggregation.
StrumerJohn
Tutor
Apr 27, 2020
Is this ever going to get fixed or did Netgear just give up on their top tier modem?
- shnushnu
  Initiate
  May 01, 2020
  Holy cow, its end of april 2020 and i just got this and the $1000 wifi6 orbi setup and i'm seeing the exact same link aggregation throttling everyone has... How is this not fixed as yet?
  - DirtyPatriot
    Guide
    May 21, 2020
    Same here this is shocking for a huge company like Netgear. they need to do some PR work here.
AdeptMaven
Guide
Aug 20, 2020
Firmware V2.02.05 appears to fix the issue. I've had link aggregation set up for about 16 hours now and no issues. Previously the speed would have reduced after 2-3 hours.

Cm1200>RAX120
- FURRYe38
  Guru - Experienced User
  Aug 20, 2020
  Please report your findings in another day or two...
  AdeptMaven wrote:
  Firmware V2.02.05 appears to fix the issue. I've had link aggregation set up for about 16 hours now and no issues. Previously the speed would have reduced after 2-3 hours.
  
  Cm1200>RAX120
  - DirtyPatriot
    Guide
    Aug 20, 2020
    I've been stable for 5 days now. Have been running speed tests every evening. Still pulling 1200down 42up. I am considering this issue finally resolved. Crazy it took a year but grateful nonetheless.
FURRYe38
Guru - Experienced User
Aug 24, 2020
Any progress on this for you? New FW seems to resolve this.
Pokemaniac wrote:
If I hook up my CM1200 to my router (an Asus RT-AX88U) in Link Aggregation mode, it seems to be consistenly slow down to only around 66-ish% of the full connection speed after somewhere between 24 and 48 hours of uptime. The only thing which seems to fix this is rebooting the CM1200. Additionally, I've had it running for at least a week now with Link Aggregation disabled, and I'm not seeing any slowdown, so it would appear that Link Aggregation is related to the problem.

The firmware of the CM1200 shows up as V1.01.02, for reference.
- flynhawaiian
  Star
  Aug 25, 2020
  now if netgear would just push the firmware update to something we purchased it would be nice, or provide us with a discount for the purchase of a new unit.
  - anthonypants
    Tutor
    Aug 25, 2020
    Netgear can't push this firmware down to your modem, that's your ISP's job.
    
    And don't bother calling your ISP to complain about it, because those CSRs will tell you that flashing firmware is your job.
    flynhawaiian wrote:
    now if netgear would just push the firmware update to something we purchased it would be nice, or provide us with a discount for the purchase of a new unit.
anthonypants
Tutor
Sep 24, 2020
CM1200 firmware version V3.02.01 just hit Comcast this morning.
- Topology
  Virtuoso
  Sep 24, 2020
  Are other community members seeing a CM1200 firmware upgrade to V3.02.01 with Comcast/Xfinity?
  
  According to this thread, the new firmware enables upstream OFDMA channels – and, was installed on users’ CM1200 modems by Charter, only to be subsequently downgraded.
  - retate
    Star
    Sep 24, 2020
    My CM1200 (Xfinity gigabit service in the St. Paul, MN area) is on V2.02.05 and has been rebooted today due to a 10% to 20% packet loss. It has been on V2.02.05 since the rollout a few weeks ago with no problems until today.

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CM1200 slows down after 24-48 hours of uptime when using link aggregation