If you have an error 11 that appears on your camera when attempting to connect with the app, a full reset is required. 

1) Make sure in the App Store that you have the latest update of the Exposio mobile app. 

2) Reset the camera's WiFi settings: How to reset the WIFI settings on the SL3

3) Dissociate your camera in the Exposio mobile application: How to dissociate a camera from your device

4) Repeat the steps of connections between the SL3 camera and the mobile application: First steps with the SL3/250D Pro Kit - WiFi (iOS)