[0.18.18] Extremely slow save downloading speed (Krastorio Mod )

[Omti]

I've been trying to play the Krastorio mod in multiplayer with a friend, and we've got the issue that our download speed is super slow (2-3 kb/s) for some reason.

We don't know what the reason might be. There is no difference if I host or he hosts.

In case it's really necessary I can upload the mods folder, but it's 265 mb, and I'd really rather not. We're using Krastorio version 0.9.11, the problem occured first on Karstorio version 0.9.09. We're using no other mods.