Diagnose Win10 download speed problems

[ftarz]

I'm having trouble with a Win10 box that does 400Mb/sec after rebooting but drops to 10Mb/sec after a few minutes. The box is current on updates and uses wired Ethernet. At the same time that the download speed is dropping, it remains full speed on my Linux box on the same network segment. A reboot returns the download speed to normal, but after letting the box sit for 30 minutes with no activity the download speed drops again.  I've debloated the Win10 box but no change.

 

Does anyone know where to start looking?

 

Frank

[C2dan88]

Open windows run command (Win + R) and type ncpa.cpl

Right click your ethernet connection and select status what is stated for connection speed 

Look at task manager > performance > ethernet. Is there signs of large amount of data being sent/received

 

Does leaving windows idle in safe mode also reduce the download speed.