When you open up the app without a connection, you will get that connection error message, all is normal there. If you turn your wifi on while in app, no biggie, you will connect as normal if you simply try again after connecting.
But, if you need to leave the app to connect, like by going to settings and such, this message will remain and you will be unable to connect to the game in spite of a connection being present.
But, you can simply either disconnect and then reconnect to your wi-fi, or restart the app to bypass this issue. Still, just a minor thing.
Device: samsung SM-T350; Android 7.1.1;
Android App v0.2.13 issue