Unreliable internet access

Internetaccess behaves strangely on my system. I love void and i really want to make it work, so im posting this in hope of someone having an idea.

Downloading things from the internet is sort of slow, because the speed jumps between 100% and 0% all the time. The UI in steam for example just shows, that i download with 5MB/s, but the graphs in btop jumps from 0MB/s to 10MB/s in intervals of about 1 second. (Not reliably 1 second, just a average) Transfering files to my nas on the same connection works with 10MB/s from start to finish. When im on Windows (yes i still dual boot), the internet also works fine. When i plug my computer into another networkswitch, the speed drops to 0-10% for some reason. But only on void. I had some debian thingy before (pop-os), and the internet on that worked fine. (I have not stress tested it, but i cant remember it working poorly like now)

This is my system: OS: Void Linux x86_64 Host: MS-7C91 2.0 Kernel: 6.12.31_1

I tried some things, but currently im running NetworkManager (no difference to tools like dhcpcd)

Forgive me, when i have done obvious upsies. Im a noob in the grand sheme of things.

I appreciate any helping hand! If i could supply some more info, im happy to do so!