Download keeps breaking?

Hello,

For some time now, I've been having a problem where virtually every download, regardless of whether it's in the browser, Ubisoft, the installer, etc., crashes. When I restart it, it usually continues from that point, but then crashes again after a few seconds. So, if I stick with it and consistently restart the interrupted download, I can download the program after a while. But that's obviously extremely annoying and not always helpful. I'm surprised that it works without issues on Steam, for example.

I use a Fritz! Wi-Fi stick, which always worked well in the past.