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Modem Can Only Lock One Upstream Channel (Partial Service); Downstream Channels Normal; T3 Timeouts

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Regular Visitor

Modem Can Only Lock One Upstream Channel (Partial Service); Downstream Channels Normal; T3 Timeouts

Hello, I was just wondering if anyone had any advice for my connection troubles. I think I've definitely narrowed the problem down to a signal/modem issue. On my Netgear CM550V modem, my upstream light is constantly blinking and I am unable to lock on to more than one upstream channel based on the modem's info page. I've tightened my cables, powercycled my modem, and reset it several times to no avail. I was hoping that there was some more troubleshooting I could do on my end, but the modem itself is brand new, so I'm at a loss so far. Although the internet connection works, there are definitely latency problems and ping spikes I've noticed during testing. Thanks for your time!

 

Here's the modem information, the numbers don't seem too far out of the ordinary, yet the upstream channels refuse to lock:

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 621000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 17 621000000 Hz 1.7 dBmV 39.5 dB 0 0
2 Locked QAM256 5 549000000 Hz 1.5 dBmV 39.9 dB 0 0
3 Locked QAM256 6 555000000 Hz 1.5 dBmV 39.8 dB 0 0
4 Locked QAM256 7 561000000 Hz 1.4 dBmV 39.7 dB 0 0
5 Locked QAM256 8 567000000 Hz 1.7 dBmV 39.7 dB 0 0
6 Locked QAM256 9 573000000 Hz 1.6 dBmV 39.7 dB 0 0
7 Locked QAM256 10 579000000 Hz 1.7 dBmV 39.6 dB 0 0
8 Locked QAM256 11 585000000 Hz 1.8 dBmV 39.7 dB 0 0
9 Locked QAM256 12 591000000 Hz 1.8 dBmV 39.7 dB 0 0
10 Locked QAM256 13 597000000 Hz 2 dBmV 39.7 dB 0 0
11 Locked QAM256 14 603000000 Hz 1.9 dBmV 39.7 dB 0 0
12 Locked QAM256 15 609000000 Hz 2 dBmV 39.6 dB 0 0
13 Locked QAM256 16 615000000 Hz 1.8 dBmV 39.5 dB 0 0
14 Locked QAM256 18 627000000 Hz 1.8 dBmV 39.4 dB 0 0
15 Locked QAM256 19 633000000 Hz 1.5 dBmV 39.4 dB 0 0
16 Locked QAM256 20 639000000 Hz 1.8 dBmV 39.3 dB 0 0
 
Upstream Bonded Channels (Partial Service)
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 1 5120 Ksym/sec 35800000 Hz 41.8 dBmV
2 Not Locked Unknown 2 0 Ksym/sec 29400000 Hz 0.0 dBmV
3 Not Locked Unknown 3 0 Ksym/sec 23000000 Hz 0.0 dBmV
4 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

 

And the Event Log: There seem to the frequent T3 timeouts:

Time Priority Description
Sat Mar 14 19:05:32 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:30 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:30 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:30 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:30 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-VER=3.0;
Sat Mar 14 19:05:30 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:30 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-outCM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:09 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:09 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:09 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:09 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;;CM-VER=3.0;
Sat Mar 14 19:05:09 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:05:09 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:46 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:46 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=28:80:88:05:d7:d8;CMTS-MAC=00:01:5c:6a:08:6b;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:46 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:46 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:46 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:46 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:24 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:24 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:24 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:24 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:24 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:24 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:02 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:02 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:02 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:02 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=28:80:88:05:d7:d8;CMTS-MAC=00:01:5c:6a:08:6b;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:02 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:04:02 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=28:80:88:05:d7:d8;CMTS-MAC=00:01:5c:6a:08:6b;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:39 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=28:80:88:05:d7:d8;CMTS-MAC=00:01:5c:6a:08:6b;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:39 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:39 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:39 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:39 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:39 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:17 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:17 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;;CM-QOS=1.1;CM-VER=3.0;
Sat Mar 14 19:03:17 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.0;
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Frequent Visitor

Re: Modem Can Only Lock One Upstream Channel (Partial Service); Downstream Channels Normal; T3 Timeo

Any luck on this? I am experiencing the same exact issues with constant T3 errors as well as a single upstream bonded channel.

Does your modem also take 20 mins to reconnect after a restart?
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Regular Visitor

Re: Modem Can Only Lock One Upstream Channel (Partial Service); Downstream Channels Normal; T3 Timeo

So far no luck! You are correct: sometimes the modem takes up to 15 minutes to reestablish a connection after rebooting, and it tends to get hung up while establishing the upstream connection (and even after the connection is established the upstream light on the modem keeps blinking). Other times however it is faster to connect (2 minutes or less). It's quite baffling, but no matter how long it takes it still never locks more than one upstream channel.

 

Another detail I noted recently is that when the modem is trying to lock the upstream channels, the upstream power level jumps around from a low of 24dBmV all the way up to 57dBmV during the initial "establishing upstream connection" phase. Then once it locks it is stable. I don't know if that is helpful or not.

 

The downstream connection gets established quite quickly, and it's not showing any correctable or uncorrectable errors on any channel, so I'm still not quite sure what is going on.

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Frequent Visitor

Re: Modem Can Only Lock One Upstream Channel (Partial Service); Downstream Channels Normal; T3 Timeo

I've noticed the same things although I *do* have some corrected erros on my downstream. Since this forum seems to be getting little activity I will try switching out my splitter this weekend to see if things help.

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Frequent Visitor

Re: Modem Can Only Lock One Upstream Channel (Partial Service); Downstream Channels Normal; T3 Timeo

Question, are you even seeing service disruption? For me I AM getting the advertised download and upload speeds and never really had any issues with disconnects so perhaps this isn't even an issue?

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Regular Visitor

Re: Modem Can Only Lock One Upstream Channel (Partial Service); Downstream Channels Normal; T3 Timeo

Good question! I am getting decent performance on speed tests (download and upload speeds as advertised), but I am experiencing severe packet loss and latency issues however. Generally the connection doesn't cut altogether though.