Mavlink times out

Hi all,
I have several pairs of 3DR Radios, that I have used with APM 2.x without Problems. I am know configuring a Pixhawk, and, although the Radios still connect fine to the APMs , they will TIMEOUT when I use the Pixhawk (both with QGround Control AND Mission planner)
On Mission Planner, The Driver Name in the Dropdown right underneath the com port is empty, suggesting that the Driver is not correct or not found. I have upgraded the FTDI Driver to no avail.
The Radio showa up on the device list.
I am running Windows 10.
I have used all pairs of Radios that I have, as well as all 3 Pixhawks 2.8 , same Problem. With APM is works all the time.
Anyone has an idea?
Thanks in advance ,

Did you check that the baudrate configuration in the radio and in the Telem port that you use are the same ?

I did , same thing.