I came across this warning when switching to a new Android phone, and although I eventually found the answer on these forums, it wasn't particularly obvious - so this post will hopefully help out.
First off, like most of the popup messages on the app, it is useless, and downright WRONG!
The solution on other threads is to turn the phone onto airplane mode before turning Wifi back on to connect to the camera.
Having mobile data turned on and being connected via wifi to the camera confuses the app. Because the WiFi connection to the camera doesn't have internet connectivity, the phone tries to direct all network traffic to the mobile data connection - including trying to reach the camera. So turn off 4G, and the connection works.
Forget the fact that the error message talks about camera initialization, and the fact that it tells you to select an option that doesn't exist, and the fact that pressing either OK or Close does exactly the same thing ...