so try another settings - speed & duplex 1 Gb/s full duplex
Speed & Duplex from "Auto-Negotiation" to "1.0 GBps Full Duplex" , no change.
Bought an Intel Gigabit PCIE NIC (using the Intel® 82574L Gigabit Ethernet Controller) and I STILL GET THE SAME THING.
Tried upping the Transmission and Receive Buffers from 512 to 2048 but did nothing I still get 10Mbit upload and 800Mbit down.
Update: Bought an external USB-C > Gigabit Ethernet adapter having a Realtek-chipset and it was the same.
Tried it on my work computer and got like 300/300.
Tried booting into Ubuntu and tried the built-in NIC and got consistent results of 800/800.
So something in Windows, something with either the OS or a driver from Intel.
Reset my BIOS-settings to "optimized defaults" but no change.
I tried the default settings for the NIC and tested against speedtest (by Okta, their Windows 10-app) and also fast.com and there I get the the expected speed of around 900/900.
If I run "bredbandskollen"s CLI-tool I also get the expected speed so the problem only occurs when using their website.
I tried contacting them to bring this to their attention but received an automatic reply 😕
So everything is good, if another Swede reads this then try the CLI-Tool here:http://www.bredbandskollen.se/om/mer-om-bbk/bredbandskollen-cli/
or another service such as either:https://fast.com/
(press "Show more info" after the test to measure your upload-speed)