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Sat, Jul 11, 2020 6:00 PM

Slow Internet

Over the last two weeks my internet speeds have dropped to a dead crawl. I reset my modem and checked all the cables outside to the modem and none were loose. The cable line has no splitters or amplifiers attached to it.


The event logs on the modem show three Critical Errors that keep repeating:


Sat Jul 11 18:37:48 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:03:fa:85:b6:67;CMTS-MAC=00:01:5c:80:ea:4b;CM-QOS=1.1;CM-VER=3.0;

Sat Jul 11 18:37:25 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=cc:03:fa:85:b6:67;CMTS-MAC=00:01:5c:80:ea:4b;CM-QOS=1.1;CM-VER=3.0;

Sat Jul 11 18:37:25 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=cc:03:fa:85:b6:67;CMTS-MAC=00:01:5c:80:ea:4b;CM-QOS=1.1;CM-VER=3.0;


Not sure if it is my modem or the connection on their end. 


Here is the Xfinity connection status:


Local time:2020_07_11 19:42:34
System Uptime:1 days 18h:25m:00s
WAN IP Address (IPv4):fe80::ce03:faff:fe85:b669/64
DHCP Client (IPv4):Enabled
DHCP Lease Expire Time (IPv4):3d:15h:41m
WAN MAC:CC 03 FA 85 B6 69
eMTA MAC:CC 03 FA 85 B6 68
CM MAC:CC 03 FA 85 B6 67

Initialization Procedure

Initialize Hardware:Complete
Acquire Downstream Channel:Complete
Upstream Ranging:Complete
DHCP Bound:Complete
Set Time of Day:Complete
Configuration File Download:Complete

Cable Modem

HW Version: 1.5
Vendor: Technicolor
BOOT Version: 2.1.8_Technicolor
Core Version: 01.E6.01.22.50
Model: TC8305C
Product Type: Technicolor DOCSIS 3.0 Packet Cable 2.0 advanced cable gateway
Flash Part: 64 MB
Download Version: 01.E6.01.22.50
Serial Number: 1437408165

Downstream Channel Bonding Value

Index 1 2 3 4 5 6 7 8
Lock Status Locked Locked Locked Locked Locked Locked Locked Locked
Frequency 579 MHz 585 MHz 591 MHz 597 MHz 603 MHz 609 MHz 615 MHz 621 MHz
SNR 39.4 dB 39.4 dB 39.9 dB 39.8 dB 39.4 dB 39.6 dB 39.5 dB 39.0 dB
Power -7.9 dBmV -7.2 dBmV -6.3 dBmV -7.7 dBmV -8.8 dBmV -8.1 dBmV -8.4 dBmV -9.6 dBmV
Modulation 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM

Upstream Channel Bonding Value

Index 1 2 3 4
Lock Status Locked Locked Locked Locked
Frequency 35 MHz 29 MHz 22 MHz 16 MHz
Symbol Rate 5120 Ksym/sec 5120 Ksym/sec 5120 Ksym/sec 5120 Ksym/sec
Power Level 53.5 dBmV 52.5 dBmV 52.5 dBmV 52.5 dBmV
Channel ID 21 22 23 24
CM Error Codewords
Unerrored Codewords 2598070526 2598006783 2598004713 2598002192 2597999571 2597997562 2597995337 2597992641
Correctable Codewords 1288 986 785 948 1299 1123 1079 1416
Uncorrectable Codewords 0 0 0 0 0 0 0 0


Thanks for any help,








86.5K Messages

10 m ago

The upstream power is too high / out of spec. The downstream power is on the weak side as well.  That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.


See if anything below applies. If not, you'll need a tech out to investigate / correct the problem. Good luck !

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

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