Cable modem resetting randomly

[CalebD]

I have a purchased Arris SB8200.  It's been working fine up until recently.  Randomly, the cable modem will reset.  I see the lights on the front of the modem go through the connection sequence (they are off, and slowly turn on green and one blue).

In reading others posts, I think I might have a line problem since the upstream power requested by comcast is out of spec for the modem.  Arris' website states that for 3+ upstream connections, the power shouldn't be above 51 dBmV.  There are currently 5 channels.  The lowest is 49 dBmV and the highest is 52 dBmV.  

The event log lists some problems.  Here is a snippet.

04/21/2020 08:45	82000200	3	"No Ranging Response received - T3 time-out;CM-MAC=2c:95:69:fc:0f:f5;CMTS-MAC=00:b0:e1:72:fc:ee;CM-QOS=1.1;CM-VER=3.1;"
04/21/2020 08:45	84000500	3	"SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=2c:95:69:fc:0f:f5;CMTS-MAC=00:b0:e1:72:fc:ee;CM-QOS=1.1;CM-VER=3.1;"
04/21/2020 08:33	2436694061	5	"Dynamic Range Window violation"
04/21/2020 08:33	82001200	5	"RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=2c:95:69:fc:0f:f5;CMTS-MAC=00:b0:e1:72:fc:ee;CM-QOS=1.1;CM-VER=3.1;"
04/21/2020 08:33	82000200	3	"No Ranging Response received - T3 time-out;CM-MAC=2c:95:69:fc:0f:f5;CMTS-MAC=00:b0:e1:72:fc:ee;CM-QOS=1.1;CM-VER=3.1;"
04/21/2020 08:32	2436694061	5	"Dynamic Range Window violation"
04/21/2020 08:32	82001100	5	"RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=2c:95:69:fc:0f:f5;CMTS-MAC=00:b0:e1:72:fc:ee;CM-QOS=1.1;CM-VER=3.1;"

I contacted support and a technician cannot come out right now.  Is there anything I can do?  I don't have any splitters in the house.  There are a couple installed on the outside of the house by comcast a while ago.

[CCAndrew]

Any splitters outside are basically considered in the house, if you have access. If you have multiple, you want your modem cable outlet on the first splitter on a leg of the splitter with the lowest loss (splitters will normally have them labeled 3.5, 5.5, 7 etc). You should also look at your downstream, if you lower upstream, downstream will raise by the same amount

[EG]

The upstream power is too high. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, and latency problems.

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.

[CalebD_]

I tried a different port in my house.  It only had one splitter between it and the feed from the street.  Upstream power is 6 dB lower so hopefully that fixes the problem.

[EG]

That should give you more wiggle room. Bottom line is to live with it a while and see if the problem returns. Good luck !