Strange Network download rate limiting

Hello everyone.

I noticed that yesterday my 7750 was struggling to play back youtube 4K videos without stuttering.

Checking network throughput via Task Manager shows that it maxes out at 13-14Mbps.

Trying speed tests via fast.com backs this up , and windows updates also come in at this slow pace.

Trying speedtest.net shows my true network speed of over 400Mbps down.

I get the same speeds if I am connected directly via Ethernet or Wifi so it is not the big packet thing that other people have reported, and I have the issue both at work and at home with different broadband providers.

The machine is running the latest windows 10 version with all dell updates including the 1.9.1 bios update.

My other Dell machines are all running fine with no issues.

Upload speeds are fine showing 200Mbps or more.

Thanks for your help with this.