Windows 10: Subpar download speed with Ryzen 1800x - 2 CPU cores at 100%

Hello.

I've a problem that's bugging me since I bought my Ryzen platform (specs are on my profile), and that problem is that my download speed is subpar (it doesn't reach close to 1Gbps like my old 3930k @4.5GHz would) vs what I got with my old platform. Before I only had this problem when I enabled an Hyper-V External Virtual Switch, now the problem manifests itself even without it.
For example, below is a screenshot of a Speedtest run to my closest server which belongs to my ISP (notice how 2 cores are fully maxed out). I'm getting 835 Mbps when I should be getting around 920 Mbps:



Just look at the two cores being maxed out.

Now here is an Iperf3 (with -R flags so I can test the download speed) test inside the LAN (notice again 2 CPU cores almost maxed out). On this test I'm getting download speeds of 737 Mbps, while I should be getting around 941 Mbps:




Now the strange thing is that the upload speed isn't affected (the server is an HTPC with an AMD A8-6600k), for example, an Iperf3 test with -R flag. Notice that now I'm getting 942 Mbps:




I've already tried to disable the anti-virus & firewall software, but the result is the same.
Does anyone have an idea why this is happening? The Ryzen 1800x is way more powerful than the A8-6600K, but it (the A8) outperforms the Ryzen on download/upload speed.

Regards.

:)

 

kb4038788 messed up edge browser

I have the same exact problem.

My specs are:

Ryzen 1800x

64gb ram

Win 10 x64

 

Complete computer freeze.

Ryzen 7 8 core 1800x 3.60ghz

64gb ddr4 2400mhz ram

2x 2tb hard drives

Radeon r9 390x video with 8gb ddr5 ram

Msi x370 titanium gaming board.

I have specs covered lets just say and yes full format of the drive before install. Also up to date bios already covered, and tried a different hard drive.