Problem connecting mission planer to my pixhawk 2 with RFD868x Module

Hi everybody,
I have a boat with a Pixhawk 2 and I use Mission planer to control him.
To make the comunication between mission planer and my boat, i use RFD 868x modules.
I have made the configuration by connecting the first module to my computer and the other one to my Pixhawk. Once I have made the configuration (tx power, id etc…), I have try to click on “connect” to connect mission planer to my pixhawk.
The telemetry modules leds are solid green so all is connected but it doesn’t want to connect… It work one time during 2 minutes and after nothing. Or It’s not connecting… like if it doesn’t find the pix or if they have nothing…
I don’t know how to proceed ?