Ive been going a little nutty trying to figure out if the issue lies with my router (Nighthawk R7000), modem (SB6190), my house, Comcast or some combination. I've tried a few different modems, most recently the SB6190 and the first night the speeds were great but they've been definitely fluctuating. My plan is for 200mbps. Right now I'm seeing around 40. Additionally my modem seemed to lose its connection several hours ago.
Here are the current status numbers. I noticed two channels aren't locked (how many are supposed to be locked?) and there seems to be uncorrectables around those channels:
Yeah. Some of the downstream channels are not locking in. There is probably noise ingressing into the line somewhere at those frequencies. A tech would have the proper testing tool to locate the source.
In the interim, here are some things that you can try;
In a self troubleshooting effort to try to obtain better connectivity, 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.
Good luck !
Noise ingress is typically variable / intermittent, though it can also be steady.