If you're connecting via WiFi on your device, try turning off WiFi temporarily. Vice versa, if you're not using WiFi, try connecting to a WiFi network. Does any of that help?
Usually, the message you're seeing would indicate that your device is trying to connect to an access point that won't give access to App World, and is most likely to occur on a WiFi network with port restrictions.
I hope this info helps and is able to get you up and running.
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