Tacx not controlable

Been struggling for a week or so to connect my tacx to zwift. Been using it for 6 months connected directly via my laptop Bluetooth but this has now stopped working. Any advice?

Which Tacx trainer?
Is the firmware up-to-date?
How are you connecting it to Zwift (ANT+ or BLE)
What device are you running Zwift on (PC, Mac, iOS, ATV or Android)?

More info is needed to assist you