*** PROBLEM SOLVED ON MY OWN ***
I logged into the Router and reseted it completely.
I also connected the PS and the router with a LAN cable to make sure, they are in the same network
I installed CCAPI new (on PS and PC) and suddently it worked.
-> I think it was because of a Windows 10 Setting that put the PC into a private network status, in which only Windows was reachable.... so beware of Windows 10
Thanks for your Help...... U can close it