You may chose to use your router to connect the Motion Synth to your laptop without any internet connection at all. If your router is not connected to the internet you may get iOS prompts to login to an internet service provider. You can prevent these prompts by, within the iOS WiFi menu, tapping the 'i' symbol to the right of your network and ensuring that the auto login button is off.
Ad hoc networks between laptops and iOS devices can get 'drowned-out' by mobile phone signals in live venues. The bigger the crowd the bigger this problem becomes.
In this scenario it is better to use a MIDI cable (eg iRig MIDI) from your iOS device to the MIDI target, or set up a special wifi router that can isolate your signals from the crowd, and is connected to your laptop via ethernet.
Video instructions explaining MIDI Network Setup: https://www.youtube.com/watch?v=nb8Xgjp2J1o