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Contributor
prlaba
Posts: 8
Registered: ‎05-02-2011

My ever decreasing network speeds

I have a Comcast-supplied Cisco DPC3000 cable mobem and my own Linksys WRT160n V3 router.

 

My home network topology is:  Modem > Router > Switches > Devices

 

I have a mix of both wired and wireless devices.  All of my wired devices connect through switches; a single cable connects the router to one of the switches.

 

When I reset my router, I initially see 50-60 mbps download speeds and 10-20 mbps upload speeds on all of my wired devices (using Xfinity Speed Test). But over the next couple of days -- sometimes sooner -- that download speed gradually declines, until it's down below 1 mbps. Resetting my router immediately brings the download speeds back up to 50+ mbps. The decline is not unique to a single device; all of my wired PCs and laptops show the same reduced speeds.  Upload speeds also decrease, proportional to the download speed's decrease.

 

This downward spiral occurs on both my wired and wireless devices, so I've ruled out the usual wi-fi problem (signal interference, someone 'stealing' my wi-fi bandwidth, etc.).  I've run the speed tests using a mix of different servers and at different times of day, to rule out any anomolies caused by heavy network traffic.

 

I've also tried a bunch of experiments.  With my download speeds below 1 mbps, I disconnected the cable between the modem and the switch and plugged a laptop directly into the modem.  Download speeds returned to 50+ mbps.  That suggests to me that the problem is with my router.

 

Again with the speeds below 1 mbps, I tried resetting just the modem, leaving the router and switches 'as is.'  This time the speeds didn't change.  Again, this seemed to point to a problem with my router.

 

My router is running the latest firmware.  I'm reluctant to start playing around with my router's settings, since I am able to get 50+ mbps download speeds, if only initially.

 

What's strange is how 'linear' this decrease in download speeds seems to be.  If I reset the router in the morning (50+ gbps), it might be down to 20-30 mbps by evening.  Then, by the next morning, 10 mbps.  Then 2-3 mbps by evening,  The download speeds continue dropping steadily until I can't stand it anymore -- at one point I was getting 40 kpbs (0.04 mbps) download speeds, slow enough that my connections began timing out!

 

Before I fork out $100-$200 for a new router, I'd like to be sure that this really is a router problem and not something else.  I'm suspicious that Comcast might be throttling back my speeds over time.  (I'm not an online gamer, don't stream Netflix or other movies, etc.)  If Comcast were throttling back my speeds, could resetting my router cause the throttling to be reset?  (I think not, but I don't know enough about network protocols to be sure.)

 

Lots of networking forums describe situations very similar to mine.  Most are related to wi-fi, not wired, connections.  Most replies suggest the usual things (update your router's firmware, change wi-fi channels, change this or that router setting, call your ISP, etc.), without ever attempting to explain what might be going on.

 

Any help or suggestions would be appreciated!

 

Regular Problem Solver
broe_23
Posts: 1,858
Registered: ‎02-17-2014

Re: My ever decreasing network speeds

It helps to know what your signal levels and logs are showing on the modem.
Contributor
prlaba
Posts: 8
Registered: ‎05-02-2011

Re: My ever decreasing network speeds

No idea how to do that.  Can I log onto the modem the same as I do my router?

Contributor
prlaba
Posts: 8
Registered: ‎05-02-2011

Re: My ever decreasing network speeds

I decided to try resetting my router to its factory settings, in case a setting somehow got changed that might have caused this 'decreasing speed' problem.

 

I first walked through all of the router's settings and recorded each one.  I then reset the router to its factory settings.I then changed a few of the router's settings necessary to get wireless working again.

 

I then checked my download speed.  56 Mbps.  12 hours later, it had not decreased (generally the speed starts dropping within an hour or two of a reset).

 

So I'm cautiously optimistic that the problem has been solved.  Time will tell.