hi again,
sorry didn't have any problems untill yesterday, I don't know what exactly changed 
so far so bad,what I tried now to get it fixed was:
# limiting to single band (2.4GHz) -> crashes immediately
# turn of IPv6 -> still crashing unreguarly
but what I found out for sure is, that the router causes the trouble not the laptop.
It seems that there are known issues in the TP Link firmware, and in the Drivers of the Qualcom Wifi Card,
if you combine it, you are seriously F+++d.
For the moment I reactivated the Wifi built in the ISPs router, which is not having any problems at the moment.
Seriously having two networks is a pain (printer, network drives etc.) but at the moment it is the most simple solutions.
I will try to install OpenWRT on the TP Link and tell you how it worked out.
br