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Random; drastic drop in download speeds

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Random; drastic drop in download speeds

Good evening,

We have been eperiencing random, drastic drops in download sppeds over the past few months.  "Normal" speeds are usually around 250Mbps.  When these drops occur, speeds go down anywhere from 0-2mbps.  The network may stay stable for a day, a few days, sometimes up to a week, it really is random.

EQUIPMENT:

Arris SB8200  (wall outlet to splitter; one split to SB8200, one split to TiVo)

Google Nest WiFi router (ethernet cable from SB8200 to router)

 

SB8200 Upstream Bonded Channels:

Channel 1; power  54.0 dBmV

Channel 2; power  54.0 dBmV

Channel 3; power  52.0 dBmV

Channel 4; power  52.0 dBmV

The first two channels appear to be in spec with Arris' documentation.  Channels 3 & 4 should top out at 51.0 dBmV according to Arris.  I'm not sure what the levels should be with Xfinity, or if that even could make a difference.

Any help would be greatly appreciated.

Jeff

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Expert

Re: Random; drastic drop in download speeds

The upstream power is too high / 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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Re: Random; drastic drop in download speeds

EG,
Thank you kindly for your response It is greatly appreciated. After 2 weeks of messaging Comcast representatives they have set up a tech visit for tomorrow afternoon. I'll check the things that you listed and will go from there with a technician tomorrow. I will be reporting back. Thanks, Jeff
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Re: Random; drastic drop in download speeds

Good luck with it !



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Re: Random; drastic drop in download speeds

The technician found 3 issues.

#1  Line drop (replaced)

#2 Splitters in the box mounted to the house (removed)

#3 Non-Xfinity splitter at the cable entry point in the house (replaced)

 

The first post in this thread I listed the upstream power levels of our Arris SB8200.  Numbers from, I believe 55dBvM to 51dBvM.  After yesterday's technician stop, here are those upstream power levels.  Needless to say, our network has been stable so far.  Well, I guess I'm not allowed to post a pic, but those power levels are 41dBmV to 38dBmV.

 

I hope this helps someone.

Thanks again EG

Jeff

 

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Re: Random; drastic drop in download speeds

Much better !! Happy surfing !!



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