iOS 1.1.0 crash on launch

Hi all, have just setup duckDNS/LetsEncrypt and now find that the iOS app crashes immediately on startup. I can briefly the Home-assistant app ‘Settings’ page with my old URL, but then the app crashes before I can enter my new duckdns url. Any advice?
iPhone 7, iOS 11.1

Have you tried opening the app with Flight Mode enabled?

Thanks for the tip. Entered the url successfully in Flight mode, but when I switch data back on the app crashes as before.