Visitor

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2 Messages

Sunday, December 14th, 2025 12:56 AM

UCD invalid or channel unusable

I am experiencing daily modem resets in the morning between around 5:40 AM and 5:50 AM. My modem (Motorola MB8600) log shows repeating Critical Errors at this exact time, specifically "CMSTATUS:US_Diplexer_Mode_Change" and "UCD invalid or channel unusable". This indicates a command or maintenance action is likely being sent from the CMTS, forcing my modem offline. Is it possible that some scheduled maintenance or a repeated daily CMTS reconfiguration is affecting my node around 5:45 AM almost every day?

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Expert

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114.9K Messages

2 days ago

Please also copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.



Expert

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114.9K Messages

1 day ago

At that snapshot in time, the downstream channels 28 to 33 were on the low / weak side and channel 34's power and SNR values are out of spec. Also, the upstream is a bit on the high side and they may be intermittently fluctuating even higher to out of spec levels. 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 !

(edited)

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