No telemetry data

Hi, I have Holybro Durandal flightcontroller and these telemetry radios []. So here is the problem. When I power on the ground and air unit both have solid green led, so they are connected? I am also able to download settings and firmware to both radios in mission planner. But when I click connect button the timer starts counting and after 30 seconds it shows “no heartbeat packets received”. Tried different baud rates (mainly 57600).

yes it does happen. I have to try few times even more than 4 times in order to connect.
Make sure you use all pin ( rts cts not just rc tx). And, if still doesn’t work, try by connecting rx to rx and tx to tx( some times manufacture do mistake. Happened to me and i was snatching my hairs, luckily i give it a hunch and connect rx to rx, tx to tx) + make sure bit rate is 57 not 115.( rest default settings)