problems with FaceTime on MacBook Air

Hey guys,

I experience a problem with my FaceTime on my MacBook Air. I use FaceTime on my Mac, iPhone and iPad. All devices are registered with my Apple ID and my phone number. In the past when I got a call all three devices always ringed and I could choose on which device to answer the call. Now for around one week my Mac is not ringing anymore. iPhone and iPad are working fine but my Mac does not ring. Outgoing calls are no problem. I hv all updates, newest software, I am definitely connected to network and I already reactivated FaceTime on my Mac with activating it for both my AppleID and my Phone number. I also get the confirmation on my other devices that my MacBook is using my mail address and phone no... I have absolutely no idea what to do next :-/

Anyone else experiencing this problem or has a solution for me?

Cheers from Germany