Hi all,

for anyone following this thread, quick updates from our side.

LAN cable from the same router worked out just fine.
Ordered an ASUS USB 3.0 wifi adapter and playing with that also seems to work fine since yesterday evening.

So i believe there must be something specific with her wifi chipset that does not seem to work in a stable enough fashion for the game to work fine.
I could post some more updates in about a week or so in case anything changes.

Cheers!