Troubleshooting TouchPortal

Things I do to check when a Device (ex. iPad) cannot connect to TouchPortal:

Refresh TouchPortal App

Click the refresh button.
Close the App and Start it again.

Is the device connected

Look at he Buttom right corner in the TouchPortal UI, it should be a green circle with text like Connected to ...

Bind network adapter

Bottom left corner in the TouchPortal UI, is this set to the correct adapter?

Firewall:

Simplest is delete the Java(TM) Platform SE binary entries, and restart TouchPortal. When you update Java, the paths to javaw.exe might be different. A clean slate always help.

Portscanner

On iOS you can use the App Ping Lite, open Port Scanner and scans the IP from 12100 to 12200. Remember to uncheck Most common ports or.
If no port is open on 12134 (or any other configured). Check binding and firewall.