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Forum Discussion
C7000-100NAS randomly drops internet connection
Hello, My C7000-100NAS modem seems to randomly drop it's Comcast connection. This happen on 2.4 ghz, 5 ghz, and wired connections. There is no pattern, however the dropped connection usually last...
C7000 started dropping connection yesterday. Comcast does not appear to be the issue. Logs on the router make it hard to pinpoint what really is going on. I am suspecting the router and if that is the case I will set the thing on fire and never buy another NG prodiuct. The event logs do have some really odd date stamps.
| Time | Priority | Description |
| 2016-12-15, 01:58:51 | Critical (3) | TFTP Request Retries exceeded, CM unable to register |
| 2016-12-15, 01:58:54 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:00:28 | Critical (3) | TFTP failed - Request sent - No Response;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:00:28 | Critical (3) | TFTP Request Retries exceeded, CM unable to register |
| 2016-12-15, 02:00:33 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:01:29 | Critical (3) | DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:01:32 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:01:51 | Critical (3) | No UCDs Received - Timeout;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:01:55 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:04:29 | Critical (3) | TFTP failed - Request sent - No Response;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:04:29 | Critical (3) | TFTP Request Retries exceeded, CM unable to register |
| 2016-12-15, 02:04:34 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:04:57 | Critical (3) | No UCDs Received - Timeout;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 2016-12-15, 02:05:01 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 2017-1-8, 12:33:56 | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.1;CM-VER=3.0; |
| 2017-1-8, 12:34:32 | Critical (3) | Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.1;CM-VER=3.0; |
| 2017-1-14, 18:19:38 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.1;CM-VER=3.0; |
| 1970-1-1, 00:00:37 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:44 | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 2017-1-29, 15:34:59 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.1;CM-VER=3.0; |
| 1970-1-1, 00:00:37 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:41 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:01:11 | Critical (3) | No UCDs Received - Timeout;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 2017-3-11, 13:59:04 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.1;CM-VER=3.0; |
| 2017-3-11, 13:59:10 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.1;CM-VER=3.0; |
| 2017-3-11, 13:59:11 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.1;CM-VER=3.0; |
| 1970-1-1, 00:00:37 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:41 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:02:55 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:02:57 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 2017-3-11, 14:14:40 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.1;CM-VER=3.0; |
| 1970-1-1, 00:00:37 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:42 | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:37 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 2017-3-28, 17:00:30 | Critical (3) | Resetting the cable modem due to docsDevResetNow |
| 1970-1-1, 00:00:38 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:40 | Notice (6) | WiFi Interface [wl0] set to Channel 8 (Side-Band Channel:N/A) - Reason:INIT |
| 1970-1-1, 00:00:40 | Notice (6) | WiFi Interface [wl1] set to Channel 149 (Side-Band Channel:N/A) - Reason:INIT |
| 1970-1-1, 00:00:45 | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=a0:04:60:f5:19:a8;CMTS-MAC=00:24:c4:27:b9:39;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:51 | Notice (6) | Honoring MDD; IP provisioning mode = IPv6 |
As mentioned in an earlier post - try a "hard reset" to re-establish the default settings and possibly correct some hidden fault that is affecting the operation.
The "hard reset" will also re-establish the MAC addresses for the Cable Modem (default on the nameplate), plus the MAC addresses for the LAN port and the INTERNET port. The later are sequental (in last 2 numbers) to the default Cable Modem MAC address. After the hard-reset, change the "default" login username and password for the Cable Modem (for security), and reset the Internet password(s) to those previoulsy used - this should allow all previously "attached devices" to connect. Leave all other settings alone until you can determine if the problem is corrected.
That isnt a fix. its a bandaide. root cause needs to be determined and addressed.
Depends on how long the Bandaide lasts. Possibly the ISP is changing a setting not available for endusers to access and a "hard reset" is the only approach.
Another question for "lost internet service" - folks should determine (if possible) if the wreless connection between the PC and Modem/Router is failing, or if the ISP feed to the Modem is failing. If a hard drive (for example) is attached to the LAN port of the Modem/Router, and the PC can read and download a file from that drive, yet unable to reach the internet - then that would indicate an problem with the ISP feed or Modem's operation. If the PC can not reach a LAN connected device, then that might indicate an issue with the PC's WiFi adapter or the Router's operation.
Regarding the PC's WiFi adapter - items to check are: set to max power at all times, and not allowing the PC to turn off the adapter to "save energy". These settings are OK for desktops, but might drain the battery on laptops.
It is difficult to troubleshoot a "combined" modem/router device, since the issues are difficult to separate - i.e., is it the ISP's signal, the modem, the router, the PC's adapter, etc. Installing a LAN device can help to separate some of the issues, but not all.
I can appreciate your reply and I do agree a process of elimination needs to happen in order to determine the root. My snarky comment about a reset being a bandaide is simply that a hard reset does not change the hardware or the firmware of the router. Yes, it can reset data parameters and it can solve sync issues, but it does not solve the bits that created the problem in the first place. Doing a reset is not a perm fix. Be asured, proper network troubleshooting has been done. When all 20 devices (hardwired and wireless) drop internet at the same time, I am very confident it is a router issue. It is not a LAN issue. All devices have their permitted LAN functionality even when the internet drops. Even checked the 4 swtiches on the network just to be sure. So, this leaves the problem at the router or comcast, or both. Given that prior to the C7000 being on our network, it was very reliable, it is very suspect.