App does not connect to JMS Air2DMX Wifi Bridge

I am using JMS Air2DMX Wifi Bride in stand alone mode. The iPad is connected to the Network and other DMX Apps work, but Photon shows an error message (check your WiFi connection). The network is shown in the settings Dialoge however.

Found out that it does not work when the Air2DMX Hotspot uses a fixed IP. Needed to switch on DHCP format to work.