a. Please check if Priva and your headset have be switched on. Usually, Priva will enter into sleep mode if disconnected for 10mins. You may need to replug the 3.5mm cable, wait for 2-15s or press the big button for 2s to activate it.
b. Most paired Bluetooth devices can reconnect to Priva within 2-15 seconds. Some might take longer, up to 1min.