Hello,
I would like to share a solution to my problem with the slower internet connection, it was constantly about 50-90% slower than in Windows, but only the download, the upload was the same. My computer is connected to the router through a switch - if I had connected it directly to the router, the internet speed would have been fine.
Device: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet
Kernel: 5.9.11-3
The solution was to remove the network-r8168 driver in the Hardware configuration.