New/remodeled house so Tech ran all new line from the pole to the house, which tied into all new lines within the house. I split the line as the router is next to the cable box. I'm on the gigabit plan, but have never seen download speeds (over wifi) above mid-400s (but upload are around 40), then added the Xfi Pods today to try and help speeds in the basement for the X-box that has been lagging (dropping to around 30), but no real improvement (yet - apparently that can take a week?). So investigated online which directed me to look at my gateway and stumbled onto the below screen shot (my Gateway is a new ArrisTG3482G) - is this an issue that is causing my slower speeds?
The upstream power is on the high side (channel 2 is already out of spec) and it 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, 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, and if none of this applies, then perhaps it's best to book a tech visit to investigate and correct.
There is a 3-way splitter at the drop outside, where the Tech installed it so that we then have dedicated lines to 3 separate rooms. Then I split it again at the TV as this was the most central place for the Gateway. Both splitters are Comcast-provided CommScope (SV-3BG and SV-2G respectively) 5-1002 MHz splitters. I do note I previously had the gateway in my office (so only subject to the initial 3-way splitter) and the speeds were the same (mid-400's) but the range for the entire house was bad, so I moved it out next to the TV. I was ignorantly happy with mid-400 speed until I tried to solve why it dropped so dramatically for the basement X-Box (fluctuates from 17 to 60) which is maybe 40 feet away feet in a direct line, and realized I was paying for gigabit.
The Tech I got for the install was brand new, and apparently struggled to install from the pole (my wife was here for it), but his overall install appears clean and well done - would he have verified the speeds before leaving? My first experience with this new setup was just after a neighborhood outage (of which we have had a couple since with Xfinith crews in the neighborhood doing work) and the first thing I did was have to reboot the gateway, then tested the speeds to mid-400. So will a tech visit help?
Also, our HP printer that we have had for years and has never been a problem, seems to now only intermittently be discoverable by each of the various computers in the house over the wifi network - not sure if that is related?