I bought and assembled a new PC. It runs on Gigabyte H110 based MOBO, i3 6100 Skylake CPU, no dedicated GPU card, 8GB DDR3 memory, SSD disk. Ever since I installed an OS on it (Windows 10 N first and soon after that Solus OS 1.2 in dual-boot) I am having problems with networking.
My network looks like this:
PC (Ethernet Realtek) -> Cat5e STP (SF/UTP shielding) 10m cable -> LAN port in my ISP provided ZTE router -> ISPs network.
OK. Now the problem. I pay for 70Mbps download speed with WiFi my other devices are able to pull 40-45Mbps due to high interference. OK. Via that Ethernet cable I get anywhere between 1-4Mbps, mind you - not MBps it's literally Mbps. I installed Realtek network drivers and one time I managed to get like 71Mbps out of it. Later it just went back to 1-4Mbps, sometimes as high as 10Mbps. On Linux after some initial problems with kernel modules not having the proper driver (thus not connecting at all) I managed to get the same results as on Windows.
If I connect my phone to WiFi and to that PC via USB to tether connection via USB I get 40Mbps on that desktop PC as well.
Any ideas? Where would you look for errors/misconfiguration?
edit 1: I tested the same cable/router port on my ASUS laptop. I got 68-71Mbps. Then I tried tethering WiFi via USB from my smartphone and it got to 50Mbps. The low speed issue is happening on both Windows and Linux. When I use USB to receive connection - does it use the onboard network card?