iPads disconnect from Wi-Fi when they’re in sleep mode. When this happens, the T-Box Mate app also loses Wi-Fi connection.
When you bring the iPad out of sleep mode, your device automatically connects to the last connected Wi-Fi network. When you open the app again, you’ll be presented with the last screen viewed, or you’ll have to reconnect the app to your T-Box.
Your iPad’s default setting is to go into sleep (auto-lock) mode after 2 minutes. If you’d like to increase that time, go to your iPad settings and choose general, then choose auto-lock, and then set the time you want.