Here is what I mean about matching the TX packet rate to the RX packet rate. This is configured using the SYS --> Tools --> ExpressLRS.
The TX packet rate is what will ALWAYS be used when the RX connects to the TX when it boots up. So as an example, the screenshot below shows my TX is using a 333HZ packet rate.
To see what the RX is configured to, scroll down and select >Other Devices
Your RX should then show in the list. Select it and hit enter. In my current setup, it is a RadioMaster ER5A.
Now I see what the default packet rate is set to for the RX. As you can see, it is set to 100Hz.
The problem with this is, when it boots up, it will go through a round robin test of EVERY packet rate till it finds that the TX is listening at 333Hz. This takes several seconds per test. (100Hz ,50Hz, F1000, F500, D500, D250, 500Hz, 333Hz) In this case, it takes 20-30 seconds before the RX and TX are talking. THAT IS AN ETERNITY when you want to regain control of a plane in the air!
After Matching my RX to the TX packet rate, the connection is almost instantaneous.
Same thing is true if it seems like it takes a long time for the RX to connect when you plug in the battery. If it doesn't connect almost instantly, check that the RX init rate matches the TX!
Cheers!
LitterBug