Frequent Visitor
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8 Messages
T3 and T4 Timeout errors - frequent connectivity outages
I have been dealing with constant internet outages for going on 3 and a half months. I've gotten a "new" replacement MB8611 modem from Motorola and an Xfinity tech came out to run a new line from the pedestal to the house. Still getting 10 or more outages per day.
The closest I can come to a diagnosis is what the Motorola engineer who is working on this has shared with me based on his read of the modem Connection and Event Logs pages. His email:
Your coaxial network connection is pretty bad. According to the Status Connection page you provided, there are a huge amount of Uncorrected errors indicating a big packet loss on the coaxial line network provisioned by your ISP.
The power levels(Pwr) for the downstream bonded channelsshould be between -7 and +7 dBmV(closer to zero the better it is) and within a 3dBmV range with all the downstream channels.
The upstream bonded channels should have power levelsbetween 38 - 50 dBmV, the optimum is 45 dBmV. Additionally, it's important that all upstream channels have power levels within a 3 dBmV range of each other.In the Event Log I see many T3 timeout events. T3 timeout errors mean that the cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS.
The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages.
T4 timeout events which are also present in your event are a more severe error than T3, meaning the modem lost the connection because of a lack of response from the ISP.I recommend contacting your Internet Service Provider (ISP) and requesting a technician visit. Ensure that they rectify and optimize all the values to fall within the specified optimal parameters.
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Downstream Bonded Channels
Channel |
Lock Status |
Modulation |
Channel ID |
Freq. (MHz) |
Pwr (dBmV) |
SNR (dB) |
Corrected |
Uncorrected |
1 |
Locked |
QAM256 |
4 |
405.0 |
5.1 |
43.7 |
0 |
0 |
2 |
Locked |
QAM256 |
1 |
387.0 |
4.8 |
43.8 |
0 |
0 |
3 |
Locked |
QAM256 |
2 |
393.0 |
4.9 |
43.7 |
0 |
0 |
4 |
Locked |
QAM256 |
3 |
399.0 |
5.0 |
43.6 |
0 |
0 |
5 |
Locked |
QAM256 |
5 |
411.0 |
5.2 |
43.7 |
0 |
0 |
6 |
Locked |
QAM256 |
6 |
417.0 |
5.3 |
43.8 |
0 |
0 |
7 |
Locked |
QAM256 |
7 |
423.0 |
5.3 |
43.8 |
0 |
0 |
8 |
Locked |
QAM256 |
8 |
429.0 |
5.4 |
43.8 |
0 |
0 |
9 |
Locked |
QAM256 |
9 |
435.0 |
5.5 |
43.8 |
0 |
0 |
10 |
Locked |
QAM256 |
10 |
441.0 |
5.5 |
43.8 |
0 |
0 |
11 |
Locked |
QAM256 |
11 |
447.0 |
5.7 |
43.8 |
0 |
0 |
12 |
Locked |
QAM256 |
12 |
453.0 |
5.8 |
43.8 |
0 |
0 |
13 |
Locked |
QAM256 |
13 |
459.0 |
5.8 |
43.9 |
0 |
0 |
14 |
Locked |
QAM256 |
14 |
465.0 |
5.8 |
43.9 |
0 |
0 |
15 |
Locked |
QAM256 |
15 |
471.0 |
6.0 |
43.9 |
0 |
0 |
16 |
Locked |
QAM256 |
16 |
477.0 |
6.0 |
43.9 |
0 |
0 |
17 |
Locked |
QAM256 |
17 |
957.0 |
8.8 |
43.9 |
0 |
0 |
18 |
Locked |
QAM256 |
18 |
963.0 |
8.8 |
44.0 |
0 |
0 |
19 |
Locked |
QAM256 |
19 |
969.0 |
8.7 |
43.9 |
0 |
0 |
20 |
Locked |
QAM256 |
20 |
975.0 |
8.5 |
43.9 |
0 |
0 |
21 |
Locked |
QAM256 |
21 |
981.0 |
8.3 |
43.9 |
0 |
0 |
22 |
Locked |
QAM256 |
22 |
987.0 |
8.0 |
43.8 |
0 |
0 |
23 |
Locked |
QAM256 |
23 |
993.0 |
7.7 |
43.6 |
0 |
0 |
24 |
Locked |
QAM256 |
24 |
999.0 |
7.5 |
43.2 |
0 |
0 |
25 |
Locked |
OFDM PLC |
193 |
774.0 |
9.5 |
44.2 |
1746915 |
0 |
Channel |
Lock Status |
Channel Type |
Channel ID |
Symb. Rate (Ksym/sec) |
Freq. (MHz) |
Pwr (dBmV) |
1 |
Locked |
SC-QAM |
1 |
5120 |
16.4 |
36.3 |
2 |
Locked |
SC-QAM |
2 |
5120 |
22.8 |
36.5 |
3 |
Locked |
SC-QAM |
3 |
5120 |
29.2 |
36.5 |
4 |
Locked |
SC-QAM |
4 |
5120 |
35.6 |
36.5 |
What more can I provide? I really want to email someone senior at Xfinity to share the log info, if that would help but there doesn't seem to be any sort of option that I've seen that would allow me to do so... yet.
I feel like I have hit a wall in the standard tech support escalation and need senior tech support or I'm just going to keep going in circles.
Yesgaro
Frequent Visitor
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8 Messages
1 day ago
Just an update to include more additional T3 and T4 errors in the logs from this morning... had multiple outages in the middle of work calls where I was screen sharing which was unpleasant.
02:41:23
Fri May 9 2025
Critical (3)
Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
02:41:50
Fri May 9 2025
Critical (3)
UCD invalid or channel unusable;
02:41:55
Fri May 9 2025
Critical (3)
No Ranging Response received - T3 time-out;
02:42:21
Fri May 9 2025
Critical (3)
UCD invalid or channel unusable;
Time Not Established
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;
Time Not Established
Critical (3)
UCD invalid or channel unusable;
08:15:42
Fri May 9 2025
Critical (3)
UCD invalid or channel unusable;
Time Not Established
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;
Time Not Established
Critical (3)
UCD invalid or channel unusable;
Time Not Established
Notice (6)
Honoring MDD; IP provisioning mode = IPv6
08:18:39
Fri May 9 2025
Notice (6)
DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;
08:18:48
Fri May 9 2025
Critical (3)
UCD invalid or channel unusable;
08:24:02
Fri May 9 2025
Notice (6)
CM-STATUS message sent. Event Type Code: 24; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;
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