NETGEAR is aware of a growing number of phone and online scams. To learn how to stay safe click here.

Forum Discussion

NightHawkNancy's avatar
NightHawkNancy
Guide
Mar 07, 2022

C7800 Keeps Disconnecting and/or Very Slow

Our C7800 Nighthawk cable modem router recently started disconnecting or getting VERY slow speeds out of the blue. We purchased it in April 2021 and it worked flawlessly up until the middle of last m...
Troubleshooting
plemans's avatar
plemans
Guru - Experienced User
Mar 07, 2022

You have errors in the cable connections page plus your logs are indicating issues. 

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, bad/old/cheap connectors, or corroded connections. Replace them if you do.
If you can, simply connect the modem right where the coax comes into the home. This prevents wiring in the home from being the issue. I know you said you don't have an outlet but grab an extension cord and try the connection. 

 

NightHawkNancy's avatar
NightHawkNancy
Guide
Mar 08, 2022

Thanks for the reply plemans ! I removed the splitter from the coax line and connected the Nighthawk directly to where coax comes into the house. Cable appears to be in good condition. WiFi dropped out multiple times since moving it. 

 

Below is the latest Cable Connection report and Event Logs. Does this appear to be a hardware issue or ISP issue?

 

 

Cable Connection
Frequency start Value 
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect. 
Starting Frequency
 
 
<tabindex=-1>Startup Procedure</tabindex=-1>
ProcedureStatusComment
Acquire Downstream Channel747000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
SecurityENABLEDBPI+
IP Provisioning ModeHonor MDDIPv4 only
 
 
<tabindex=-1>Downstream Bonded Channels</tabindex=-1> 
ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUncorrectabables
1LockedQAM25631747000000 Hz7.3 dBmV40.1 dB278116
2LockedQAM2561561000000 Hz9.5 dBmV42.3 dB00
3LockedQAM2562567000000 Hz9.9 dBmV42.8 dB00
4LockedQAM2563573000000 Hz10.5 dBmV42.9 dB00
5LockedQAM2564579000000 Hz10.7 dBmV43.0 dB00
6LockedQAM2565585000000 Hz11.1 dBmV42.9 dB00
7LockedQAM2566591000000 Hz11.4 dBmV43.1 dB00
8LockedQAM2567597000000 Hz11.7 dBmV43.2 dB00
9LockedQAM2568603000000 Hz11.4 dBmV42.8 dB00
10LockedQAM2569609000000 Hz10.8 dBmV42.5 dB00
11LockedQAM25610615000000 Hz10.4 dBmV42.6 dB00
12LockedQAM25611621000000 Hz10.3 dBmV42.1 dB00
13LockedQAM25612627000000 Hz10.2 dBmV42.3 dB00
14LockedQAM25613633000000 Hz10.0 dBmV42.3 dB00
15LockedQAM25614639000000 Hz10.3 dBmV42.3 dB00
16LockedQAM25615645000000 Hz10.6 dBmV42.1 dB00
17LockedQAM25616651000000 Hz10.9 dBmV42.3 dB00
18LockedQAM25617657000000 Hz11.3 dBmV42.4 dB00
19LockedQAM25618663000000 Hz11.5 dBmV42.4 dB00
20LockedQAM25619669000000 Hz11.2 dBmV42.3 dB00
21LockedQAM25620681000000 Hz10.5 dBmV42.1 dB00
22LockedQAM25621687000000 Hz10.1 dBmV41.9 dB00
23LockedQAM25622693000000 Hz9.7 dBmV41.9 dB120
24LockedQAM25623699000000 Hz9.6 dBmV42.0 dB110
25LockedQAM25624705000000 Hz9.4 dBmV41.7 dB90
26LockedQAM25625711000000 Hz9.4 dBmV41.9 dB540
27LockedQAM25626717000000 Hz9.4 dBmV41.8 dB500
28LockedQAM25627723000000 Hz9.6 dBmV41.8 dB6530
29LockedQAM25628729000000 Hz9.5 dBmV41.8 dB11246
30LockedQAM25629735000000 Hz9.1 dBmV41.5 dB10896
31LockedQAM25630741000000 Hz8.3 dBmV41.1 dB14975
32Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
 
 
<tabindex=-1>Upstream Bonded Channels</tabindex=-1> 
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA52560 Ksym/sec18000000 Hz39.5 dBmV
2LockedATDMA75120 Ksym/sec31000000 Hz41.8 dBmV
3LockedATDMA65120 Ksym/sec24600000 Hz40.8 dBmV
4LockedATDMA85120 Ksym/sec37400000 Hz43.0 dBmV
5Not LockedUnknown00 Ksym/sec0 Hz0 dBmV
6Not LockedUnknown00 Ksym/sec0 Hz0 dBmV
7Not LockedUnknown00 Ksym/sec0 Hz0 dBmV
8Not LockedUnknown00 Ksym/sec0 Hz0 dBmV
 
 
<tabindex=-1>Downstream OFDM Channels</tabindex=-1> 
ChannelChannel IDIndicatorSubcarrier Zero FrequencyActive Subcarrier Number RangeTotal CodewordsUncorrectable Codewords
132Non-Primary428600000 Hz1528 ~ 2567192437525
20Other0 Hz0 ~ 000
 
 
<tabindex=-1>Upstream OFDMA Channels</tabindex=-1> 
ChannelUpstreamIsMutedRanging StatusSubcarrier Zero FrequencyActive Subcarrier Number RangeSymbols Per FrameTx Power
1 Other0 Hz0 ~ 000 dBmV
2 Other0 Hz0 ~ 000 dBmV
 
 
Current System Time: Tue, Mar 08, 2022 16:40:42 

 

 
EVENT LOG

 

 
 
 
 
TimePriorityDescription
2022-03-08, 12:26:25Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
2022-03-08, 12:26:21Notice (6)TLV-11 - unrecognized OID;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedWarning (5)DHCP WARNING - Non-critical field invalid in response ;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)DHCP FAILED - Discover sent, no offer received;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedNotice (6)Honoring MDD; IP provisioning mode = IPv4
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2022-03-08, 11:52:22Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)DHCP FAILED - Discover sent, no offer received;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)DHCP FAILED - Discover sent, no offer received;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 16:22:34Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 16:17:43Critical (3)16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 16:17:43Critical (3)Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 16:17:33Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 16:17:28Critical (3)16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 16:17:28Critical (3)Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 14:05:56Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 13:52:38Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 11:24:03Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2022-03-07, 11:20:49Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=9c:c9:eb:87:d9:b0;CMTS-MAC=00:01:5c:b7:10:91;CM-QOS=1.1;CM-VER=3.1;

 

    • plemans's avatar
      plemans
      Guru - Experienced User
      Mar 08, 2022

      You've still got some indications of line problems in the logs. And now your power is a touch high. 

      Not sure what splitter you had in line but your power jumped significantly from removing the one you have. 

      Try putting a decent quality double splitter back in line. Maybe a triple. 

      Just make sure its a decent quality. the channels you had issues with (hz not just channel number) cleared up but now others have errors. 

      Try that first. 

      and once you do that, clear the logs out so we know that anything new on there is from after the change. Not sure if you're log has events from befor the change. 

       

       

      If it doesn't help, the isp might need to check the line. 

      • NightHawkNancy's avatar
        NightHawkNancy
        Guide
        Mar 08, 2022

        plemans this is the only one I've got access to at the moment and was the one I had on originally.

         

        Antronix CMC2004H 

         

        Is there a different one you'd recommend using? 

         

        I've got a MicroCenter nearby...