Probably caused by UDP broadcast packets being dropped by router/firewall. Make sure your router/firewall allows UDP broadcasts and VRidge.exe/Riftcat.exe are marked as allowed applications.
You can also try connecting manually. Please pick non-Automatic network interface on the list below.
After picking connection, an IP address will be displayed. Please tap [Connect manually] on your mobile and enter your IP address. If you see error message, please let us know what kind of message is displayed (re-type first 5 words or make a screenshot).
If it's ECONNREFUSED it may mean that firewall is blocking your connection.