I have had an SB6183 working great for probably a year. I noticed slow internet today so I decided to do a speedtest from a wired connection. I am getting 12/4 using multiple sites. I am on Blast Tier and have been getting 100/12 consitently. I think this change happened recently in the last 24 hours. I have not connected directly to the modem yet since but I don't think it is my router. I have attached my Status information from the modem.
The upstream power is too high and may be intermittently fluctuating even higher out of spec. That can cause random disconnects, spontaneous re-booting of the modem, and speed 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.
Before you do anything else, test directly connected to the modem. (You'll have to powercycle your modem). You need to know if you have a signal/modem issue or if you have a router issue. You gotta' do the basic troubleshooting so you aren't chasing your tail.
The high upstream power should still be addressed here as it may be a problem just waiting to happen even if it *may* not be now. More wiggle room is always better ! Shooting for it to be around 45 dB is desirable.