I have exactly the same issue. Trying to connect a Samsung Galaxy A3. All software was transferred from my previous phone, but I have uninstalled Prey and re-installed it. I can log in without difficulty on my PC, so I know the account details and password are correct, but all I can get on the new phone is "Prey couldn't connect to the web Control Panel. Check your settings and try again". What settings am I supposed to check? The phone connects to the internet as it should - after all, I have just downloaded Prey.