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SBG8300 & Speed / Connectivity Issues

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SBG8300 & Speed / Connectivity Issues

I pay for the Gigabit Speed service and bought the Arris SBG8300 as approved by Comcast for Gigabit Speed service.  I am unable to get quality service with download speeds in the 10-30 Mbps range (connected to ethernet), but often below 10 Mbps and dropping off completely.  I believe I am having similar issues that others seem to be having with the Arris SBG8300 in regards to upstream  / downstream power levels and was hoping to get some help / feedback on these issues and how to approach Comcast and get these handled.  As of note, what is weird is when first connected everything seemed to work fine for the first 2 weeks, but hasn't worked for 2-3 weeks now with Comcast saying everything is fine and Arris' tech support saying my power levels aren't right and to reach out to Comcast.  Comcast support, when I am able to get in touch, doesn't appear to understand the issues I am trying to explain (which, given my elementary understanding of all of this, is hard to explain).  


Here are my specs:


Downstream Levels 

Upstream Levels 


Per Arris' Guidelines, Downstream Power Levels at 256QAM are supposed to have SNR levels 30-33 dB or greater depending on power.  My dB levels dip below 30 on Channel Bonds 6-11 & 20 and the power level is pretty much outside the  -15 to -6 dBmV range from Channel Bond 5-12.  


Per Arris' Guidelines, Acceptable Upstream Power Levels are +61 dBmV to 45 dBmV.  I consistently get ~43 dBmV.  


My understanding is that the Arris guidelines are not accurate, but if that is not the issue, I'm not sure why I am unable to get solid connectivity per my plan.  


Any help would be appreciated!  If any additional information is needed, I'm happy to provide.  Thanks in advance.


Re: SBG8300 & Speed / Connectivity Issues

The upstream power is fine ! Forget what Arris says. That seems to be their canned response about the upstream power lately........


It's the downstream power and the SNR's that are out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

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.

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