It is not possible for us to determine what the difficulty may be. A failsafe event can happen when there is a lot of interfering signals in the air, it can happen if the transmitter has some kind of failure, it can happen when the model is flown out of range, and it can happen when something in the model can interfere with the signal coming into the receiver. All possible sources must be investigated.
A failing component outside of the receiver could also feed a bad signal back into the receiver and cause interference. Many possibilities for the cause of a failsafe event.
thank you Bill,any case registered due to wifi routers?