Dell XPS 13 9360 (8th Gen) - Killer Wireless-AC 1535

So, here is the deal:

Most or almost networks have miserable wireless connection.

I tried to change wifi channels on most routers. Also tried to change the protocol or whatever, but some routers only have g/n, not ac.

At this very moment, I'm downloading a (weak) game on steam, at 33-55 KB/s.