PX4 won't connect on 3.5.3

ArduCopter Copter 3.5
1

Old PX4IO+FMU stack won’t connect over USB in MP. Works fine on 3.4.6 , times-out on 3.5.3. Is px4 not supported anymore , should I stick with 3.4 ?

2

Solved by flashing with through “Force PX4 bootloader”