Visitor
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2 Messages
Home router modem synch and reboot reconnection issues
I'm having an ongoing cable modem connectivity issue and probably need a technician visit to inspect the line/plant serving my address.
Summary: My modem at times repeatedly fails to complete DOCSIS registration and cycles through partial-service states when I perform a modem reboot. In addition, I get T3 timeouts all day long. Occasionally just about every day I get synch issues as well.
What the modem's event log shows:
- 3 of 5 upstream channels (channels 2, 3, and 4) always show as "Not Locked" on the modem's status page; only channels 1 and 5 remain locked.
- Repeated "No Ranging Response received - T3 time-out" and "Ranging Request Retries exhausted" errors, often in sustained bursts (one episode ran continuously for ~25 minutes across multiple channels).
- On one day, 8 separate "SYNC Timing Synchronization failure - Loss of Sync" critical events were logged.
- Most recently, I captured a clear registration-failure loop: the modem loses sync, restarts its registration process (visible as a burst of placeholder "Dec 31 1969" timestamps, which is the modem's default clock before it re-acquires accurate time from the network), fails upstream ranging multiple times in a row, briefly enters "TCS Partial Service," then loses sync again - repeating this full cycle at least 3 times over roughly 10 to 15 minutes.
- I also observed this registration-failure pattern occur immediately after a manual modem reboot: after restarting, Wi-Fi came back online quickly but the wired/internet connection took 7-8 minutes to fully restore, correlating with repeated failed registration attempts in the log during that window.
- Upstream power levels on the unlocked channels have read as high as 54.8 dBmV, above typical healthy range, consistent with the modem trying to compensate for a poor signal path.
Given the pattern (multiple upstream channels chronically failing to lock, combined with repeated full registration-failure cycles on reboots), this is not a single isolated event). Happy to provide the full modem event log export, model/MAC address, or screenshots of the channel status page if helpful. The modem is a Motorola MG8725 and brand new just a month ago. I had similar issues with the previous modem as well, but only just now dove deeper into the details of these mode event logs. Thinkig something is amiss in my connection or interference.
EG
Expert
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121.2K Messages
5 hours ago
Yes. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.
In an effort to try to obtain better connectivity / more wiggle room, check to see if there are any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/reconfigured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage from Home Depot, Target, Wal-Mart, etc. Splitters should be swapped with known to be good / new ones to test.
Also, check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, or animal chews.
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.
Good luck with it !
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