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C6250 AC1600 Modem Router Download stream lightning bolt keeps flashing.
I have had this modem/router for about one and a half years and was connected to the Comcast TV router. Just recently I turned in the TV router and plugged the cable into the C6250 modem/router and ...
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 recently purchased a CM1150v and an ASUS rt-ax88u router. I enabled link aggregation on both the cable modems LAN ports (1&2) and the routers WAN ports (It uses WAN port and LAN 4 for WAN aggregation). Both the router and the cable modem showed that link aggregation was functional. But as a few people have mentioned here my internet speed went from 1000/35 to about 20/30 (down/up Mbps) after 12 hours or less. Also the log page in the router was getting flooded with Net_ratelimit errors because of rapid fire errors being generated. Rebooting the modem and router would re-establish normal internet speeds but the errors in the router log came right back. I've disabled aggregation in both devices for now and speed has not dropped off and error messages no longer appear. I realise my download speed (as rated by my 1Gb package) can be handled by a single network port, but sharing the load on two lines sounds and maybe I'd see higher downloads if it was working properly. Guess I'll keep an eye open on the modem firmware to see if netgear/xfinity ever flash a patch that fixes this issue.