LAN is Dead-Slow when PC is connected, that is turned off!

[2MuchMark]

Hello!

My problem is this: I have Bell Fibe 1.5Gb/s service.  The modem speed test confirms that the speed is there,  but when I test with Speedtest.net or the Speedtest App,  I get only about 450mb/s.  I used to get about 980mb/s but no longer. 

 

I tried testing from 2 different iMacs and a PC.  I tried disconnected every other device and disabling Wifi.  Nothing internally seems to be causing the speed problem.  It also does not seem to be wire related.  

 

I am using Cat6 cable everywhere,  and D-Link DGS-1016A Switches.  

 

Any suggestions are appreciated !

 

[2MuchMark]

Ok here's a head-scratcher... 

In My home lan I have a few computers and peripherals and normally get about 500mb/s download according to Speedtest.net. 

 

But when my Alienware Area 51 PC is connected, and turned off,  my speed drops to about 1Mb/s.  If I boot-up the Alienware PC,  the speed returns to normal.  Only when it's off does it slow me down to a crawl. 

 

Can anyone tell me why this might be happening? 

 

 

[intertan]

how is it connected? via ethernet or wifi

also is it a desktop or laptop

[intertan]

try right at the modem not using any of the switches

could also be a network saturation on bells end. 

 

try it various times of day with the same setup

 

also do you have any 10gb ethernet equipment? 1.5gbps is faster than most modern equipment can handle.

[manikyath]

sounds like your network hardware is encountering some sort of problem.

 

what does your network setup look like?

[wojtepanik]

1 hour ago, intertan said:

how is it connected? via ethernet or wifi

also is it a desktop or laptop

how you might be connected to wifi with turned off pc?