The upstream power is too high (already out of spec on channel #5). Some of the downstream channels have an impairment as well. 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 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 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, 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, etc.

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 !

Here's the Upstream:

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV) 1 Locked ATDMA 5 1280 39.6 48.5 2 Locked ATDMA 1 5120 35.6 48.5 3 Locked ATDMA 2 5120 29.2 50.0 4 Locked ATDMA 3 5120 22.8 50.0 5 Locked ATDMA 4 5120 16.4 52.5 6 Not Locked Unknown 0 0 0 0.0 7 Not Locked Unknown 0 0 0 0.0 8 Not Locked Unknown 0 0 0 0.0

I get Event Log warnings including: 

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;.....;CM-QOS=1.1;CM-VER=3.0;    

and

No Ranging Response received - T3 time-out;.....;CM-QOS=1.0;CM-VER=3.0; 

Problem was on the pole. The coupling was physically obviously damaged. New coupling and the system is running fine. 

Glad it got squared away ! For curiosity's sake, would you please post what the signal stats look like now ?

Hi EG, here's the "after". Looks much better to me and thanks for your help! 

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected 1 Locked QAM256 21 525.0 0.7 42.3 0 0 2 Locked QAM256 1 399.0 1.9 44.1 0 0 3 Locked QAM256 2 405.0 1.7 44.0 0 0 4 Locked QAM256 3 411.0 1.6 44.0 0 0 5 Locked QAM256 4 417.0 1.6 44.0 0 0 6 Locked QAM256 6 429.0 1.7 44.0 0 0 7 Locked QAM256 7 435.0 1.5 43.8 0 0 8 Locked QAM256 8 441.0 1.6 43.8 0 0 9 Locked QAM256 9 447.0 1.6 43.8 0 0 10 Locked QAM256 10 453.0 1.4 43.5 0 0 11 Locked QAM256 11 459.0 1.4 43.5 0 0 12 Locked QAM256 12 465.0 1.3 43.3 0 0 13 Locked QAM256 13 471.0 1.3 43.1 0 0 14 Locked QAM256 14 477.0 1.2 43.2 0 0 15 Locked QAM256 15 483.0 1.1 43.1 0 0 16 Locked QAM256 16 489.0 1.1 43.0 0 0 17 Locked QAM256 17 495.0 1.2 43.7 0 0 18 Locked QAM256 18 507.0 0.9 43.7 0 0 19 Locked QAM256 19 513.0 0.6 43.4 0 0 20 Locked QAM256 20 519.0 0.6 43.3 0 0 21 Locked QAM256 5 423.0 1.7 44.0 0 0 22 Locked QAM256 22 531.0 0.3 42.9 0 0 23 Locked QAM256 23 537.0 0.2 43.2 0 0 24 Locked QAM256 24 543.0 0.3 43.1 0 0 Total             0 0

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV) 1 Locked ATDMA 1 5120 35.6 49.1 2 Locked ATDMA 2 5120 29.2 49.1 3 Locked ATDMA 3 5120 22.8 49.2 4 Locked ATDMA 4 5120 16.4 49.7 5 Locked ATDMA 5 1280 39.6 47.7 6 Not Locked Unknown 0 0 0 0.0 7 Not Locked Unknown 0 0 0 0.0 8 Not Locked Unknown 0 0 0 0.0

Quite welcome ! The downstreams are good ! The upstreams are on the high side. There's not much wiggle room if they drift upward. They may do so when the heat of the Summer season returns. Bottom line. Live with it for a while and see. Hope things hold up for you. Good luck !

EG, re "upstreams are on the high side" would putting a splitter in line to bring these down work? Or I could add a short coax between the lightning surge and modem as I used to do (right now its screwed right onto the modem's coax male input). Or am I barking up the wrong tree becasue here there is nothing to be done on the user end about this? Also what's the optimal range for the upstreams? Thanks. 

No. A splitter will make them higher, not lower. The upstream and the downstream power work in opposite ways when it comes to overall line attenuation. You need to remove excess attenuation, not add more. 40 to 45 dB is the sweet spot for the upstream power level.

That's quite interesting, EG. I didn't realize a splitter would increase upstreams. I didn't used to have a splitter at the outside junction box, but at this last service call one was added by the tech. I used to have one inside but had removed it when looking to isolate the previous problem (which turned out to be at the pole, not in my place). I have a pretty long single run of maybe 80 feet from the outside junction box to my modem. Would it make sense to remove the outside junction box's splitter, which is acting just as an attenuator, let the higher power feed the long run, and then add the splitter back inside, closer to the modem? Or not add it back at all and run un-attenuated and then check the levels at the modem? What would you try next to optimize the levels?

Remove any unneeded splitters and see. A clean straight run is best !