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CM1200 slows down after 24-48 hours of uptime when using link aggregation
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.
150 Replies
I've got 1Gbps down and ~20-30Mbps up. I can get largely the same speeds with a single cable, but the slowdown is still kind of concerning on the off chance I can eventually get faster speeds.
this is interesting as I have not heard of it..
Is this reproducible in your environment?
which ISP are you with?
Does the problem go away if you reboot the router?
How Long does it take the issue to appear?
Both KB entries are very generic resp. talk of LAN port aggregation only FURRYe38 .
Look here - How do I set up Ethernet port aggregation between my NETGEAR Nighthawk Multi-gig Speed Cable Modem and my NETGEAR Nighthawk AX8 router? - this is one of the very misleading and poor KB entries. Multi-Gig is something different (it's used in the industry for GbE ports capable of operating at 2.5Gb and 5 Gb speed!), and there is no word of the aggregation supported/required. Just marketing rubbish - a typical "product" of the Netgear Consumer business unit. In one word: Garbage.
I agree and presume the KBs could use some updating.
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.
I have a CM1150v on firmware 2.02.04 (which is the lastest Comcast just pushed it recently in the past week) and when I turn on LAG my connection will slow down within 24 hours, it did the same on the previous firmware 2.02.03. So there is something definitely not right in the firmware that is causing this to happen and this is the first post I have seen on the Netgear forum that talks about this issue. My ISP is Comcast and my speed tier is their gigabyte plan. I have never had it last longer then 24 hours before the speed degrades.Also i might add that my CM1150v is a beta unit that I was sent in the beta test for this device on Comcast.
- I have the same thing happen on this modem as well as my Motorola Mb8600 so it’s definitely a Comcast issue. After 48 hours or so speeds drop to a max of about 650mbps with LACP enabled.
YoungSpicket wrote:
I have the same thing happen on this modem as well as my Motorola Mb8600 so it’s definitely a Comcast issue. After 48 hours or so speeds drop to a max of about 650mbps with LACP enabled.Mine drop lower then that, my download ends up well below 100Mbps typically down to about 20 or 30. First I have seen on any forum about other modems having the same problem.
- 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 speedsYea, this is exactly what I thought.
So I'm having the exact same issue -- with 802.3ad link aggregation (LACP/LAG) enabled, after about 24 hours my speeds drop from gigabit to 20-30Mbit/s. I am on firmware version 1.02.02 and hardware version 1.01. Rebooting solves the issue until it comes back. It's a real bummer and the only reason I bought this modem. I've only had it for a week or so.
- Did you read my post????? It is not the modem, it is Comcast. Read my post and do AS I did and it will fix your issues
Hey there, I did read your post, but I'm not sure that I really understand what you're on about. My cable modem frequencies are unchanged from when the issue is occurring versus when they are not. Furthermore, the signal to noise ratios (SNR) look amazing (around 42dB) and I'm showing no uncorrectable errors on any channel and little no correctable errors as well, shockingly. What were your statistics like prior to calling Comcast? I'm curious what statistic or metric I can point them to to indicate that there is a specific problem, since I'd love for it to be as easy as calling technical support and getting them to do something. With no indication that the issue is indeed on their side, it's hard to justify "raising hell", as much as we all like yelling at Comcast.
A metric that I do find interesting is that I see increased latency, upwards of 300ms RTT, to the cable modem's management IP itself (192.168.100.1) when this issue is occurring. This leads me to believe it's a runaway process of some kind on the device rather than an upstream issue.
I'm having the same issue with my CM1200 on 1Gbps service (Charter/Spectrum) and LACP, after 8-10 hours the speeds drops to sub 100Mbps and more like 20-30Mbps. I'm running Pfsense and I have found if I 1. restart the modem it works for awhile or 2. just resetting the LACP interface will restore normal performance. I had a moto MB8600 before this and never had a problem with the LACP link on it. Is there a firmware fix in the works or already out? has it been pushed to ISP for testing? Looks like I might be going back to the MB8600 and returning the CM1200
Oh, great catch. Confirmed that if I bounce (shut / no shut) the physical interfaces, performance returns to normal. This should be easy to script to run every 12 hours or so. I'm going to give NETGEAR until near the end of my return period to try to resolve this one, otherwise I'll be swapping for a MB8600 myself.
I'm going to open a ticket as well and see what happens but i'm sure even if they fix it via a firmware update it will take 6 months before Spectrum pushes it out. I know Comast is a little faster with firmware updates. Nothing like a $200 modem not working out of the box correctly but its netgear so I should know better by now.
I didn't do a search and made a similar post here Duplicate Post.
I am having the same problem on Spectrum; I have the 1Gbps service and initially connected to my pfSense router via LACP. My findings where similar in that if I reset the connection my speeds would return to normal. However my time frame for the reduced throughput was significantly lower than reported by others.
Initial speeds would be 800Mbps - 1Gbps but after four to five hours the speeds would drop to ~20Mbps with high latency. I found that resetting the LACP link would return speeds to normal. This lead to me to wondering if it was a firmware issue, maybe the hashing used on the CM1200? So I put a switch between the CM1200 and my pfSense router. This would extend the time frame between slow downs but inevitably they would return.
At this point I am have removed the LACP and I am down to one port. While my speeds are horrendous they are much better than 20Mbps; I attribute this Spectrum over provisioning or some other shenanigans.
I am attach screen shots of speed tests and a pdf that shows my signal levels.
I would like to think that Spectrum is not playing any silly games with my connection but I have no proof that they are not; my main goal is to try and figure out what is going on with this. If anyone has any recommended troubleshooting steps please let me know. I have a good amount of networking knowledge and want to get this fixed.
vkdelta- Any information on possible fixes? If I have to call Spectrum and give them hell I can but don't want to take that step until I know it is them that is the problem.
The issue is not with Spectrum. I'm on Spectrum and have been using LAGG with my MB8600 with no issues. I can hit 1.22Gbps with my pfsense build. I have also tried a SB8200 without this issue. The Netgear CM1200 LACP is broken and must be out of ieee standard because if you take one of the members down the interface will no longer pass traffic. That is one of the most basic fuctions of 802.3ad "redundancy of link if a members connection is lost"
I dont think its hash related because I tested that as well using my Cisco 3850 switch. Same results with the CM1200 but I would interrested in hearing from someone with the a multigig Netgear router with the CM1200 but I wouldn't be surprised if the results are the same.
If you want multigig with Spectrum or any other provider look at the MB8600 or SB8200 and I guess maybe the CM1100 but I have not tested that model.
I can confirm that your ISP is not the issue. After several days of bouncing around with NETGEAR support (I kept getting bounced between the switch and cable modem teams since both devices are NETGEAR) and hitting up NETGEAR on Twitter, it was clear that they don't consider this a high priority issue. Even IF they do eventually fix this problem, it may take months to roll out a firmware update since your ISP has to push that to your cable modem. Long story short, if you're going to do LACP don't even bother with the CM1200. The fact that a NETGEAR employee hasn't even replied to this thread in a long time confirms to me that they just don't care. I've had great luck with the Motorola MB8600 and I've heard good things about the SB8200 as well. I'm getting around 1.2Gbps with my MB8600 and it's been up so far for almost 10 days. See attached screenshot for evidence.
The thing that gets me is that I assume the CM1200 is just running Linux; the Linux bonding driver has supported 802.3ad link aggregation / LACP for a very long time and is very, very mature. I'm not sure what NETGEAR has done with this firmware to introduce this issue.
- Kenny
- I have been experiencing similar problems to what others have reported in this thread so thought I would provide some additional perspective.My configuration is a CM1200 (firmware 1.02.02) connected to a Netgear XS716T switch (10 gigabit switch). The CM1200 connects to Xfinity/Comcast Gigabit cable service. Cable connection data (SNR and Power) look very similar when performance is degraded to what they are when performance is good.Before performance degradation is encountered I can repeatedly measure download performance between 1100 to 1200 megabits and upload performance between 39 to 42 megabits. Performance is being measured via speedtest.xfinity.com using Chrome as the browser. The CM1200 connects via LACP to the XS716T. The traffic then passes through an OPNSense firewall with 10 Gigabit LAN and WAN interfaces connected to the XS716T switch. The desktop running the test also connects to the XS716T switch with a 10 Gigabit interface. If I run the performance test via either IE or Edge the results are less than with Chrome which I have not taken the time to understand.When speeds degrade typical results are 22 Megabits down and 16 to 22 Megabits up. The degradation occurs after a few hours. A modem factory reset, modem power cycle, or disabling and enabling the LACP/lag interface on the switch restores performance. I did notice that when I disabled and enabled the lag interface the first speed test I ran afterwards performance was only somewhat restored (139/19). When I tested again after a couple of minutes speed was 1189/41.I have not seen the degraded ping times to the CM1200 that are mentioned in this thread. I believe I have seen the LACP problem not failing over to a single connection that is mentioned in this thread, but I have not investigated.When I have checked the switch or the modem during degraded speeds link aggregation has appeared to be functioning normally. I have just started looking at port statistics on the switch, and there may be a correlation with "Total Transmit Errors" / "Dropped Transmit Frames" on the switch ports the CM1200 is connected to occurring when speed is degraded.
So recently I talked to someone with an enginering sample of the CM1200 and they confirmed Netgear is aware of this problem and have been working on it. From my understaning this problem was known by Netgear before the public product release but here we are with a broken modem on retail shelves. Don't get me wrong the CM1200 is a nice modem but with the LAGG issue is a deal breaker. Hopfuly a GBASE-T or SPF+ modem is released by a manufacturer soon. SFP+ would be awesome HINT HINT NETGEAR
cursixx wrote:So recently I talked to someone with an enginering sample of the CM1200 and they confirmed Netgear is aware of this problem and have been working on it. From my understaning this problem was known by Netgear before the public product release but here we are with a broken modem on retail shelves. Don't get me wrong the CM1200 is a nice modem but with the LAGG issue is a deal breaker. Hopfuly a GBASE-T or SPF+ modem is released by a manufacturer soon. SFP+ would be awesome HINT HINT NETGEAR
Well since they are all probably based on the same chipset the cm1150v also has the same problem, when I enable LAG on mine the speed degrades in 12 to 24 hours so once they fix this for one modem it should fix it for all of the modems having this issue.
I just got off of the phone with support about my new CM1200 connected to a RAX80 router and was told that the additional ports on the CM1200 are useless and cannot be used if port aggregation is used. I am getting the same slowdown plus if you do not have multi-gig web service that the port aggregation will not work and that it is acting properly in choking off the internet speed because it is cheating to try to get a higher speed than for what you paid.
So Netgear WAN aggregation from router to modem is useless.
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 stumbled on this thread after purchasing one of these modems. Just wondering if there has been anything new on this problem? NETGEAR?
I RMA'd my CM1200 modem, and I am still seeing the same exact slow down after a few hours. I have a 1 Gig plan, so I'm not making use of the aggregate ethernet ports. My ISP is Comcast in Northern California. Anyone know how to get their money back from Netgear?
