The wireless controllers are designed to reconnect to a nearby portal gateway should it fall offline unless it is locked to a specific portal. If the portal is not available for a while, the controller will go into a beacon cycle. This is to save the battery's life time. The beacon is as follows:
After the reader has completed the beacon cycle, it will beacon once every 24 hours until it connects to a portal gateway.
Wi-Q & WAMS 3.0 & 3.1 Controller Firmware
To force the reader to reconnect, an anti-tamper can be performed. To anti-tamper the lock, swipe a card that does not have access to the reader repeatedly until it locks out. After 60 seconds it will resume accepting the cards. Swipe the card again. On a Wi-Q controller, the blue lights should begin blinking indicating the reader is trying to communicate to the portal gateway. Verify the portal is online and in the segment.
Additionally, a soft reset can be performed at the controller. A simple unplug of the power/battery and then reconnecting it will reboot the controller and wake it up.