Hi Dimitris,
I see.
Since this is an integrated network card, you may try to check -
1. if there are any BIOS, driver updates for your board model. Especially that you just updated to Windows* 10.
2. uninstall and reinstall your network card's driver - try using driver/software provided by Asus*
3. Try reinstalling Windows* 10, if you can.
In normal circumstances, increasing the transmit buffers should fix slow upload speed that you are experiencing.
Sincerely,
Sandy