We have run into very weird behaviour using an es400. We have not experienced any issues with regards to connectivity when connected to the cable. We have now moved onto testing via 3G and we are not able to get internet connectivity unless we open IE first and perform a search. This action appears to somehow activate the 3G on the connection, which is not the case when we access our app as the first action. We can then immediately after the IE search, select our app and the connectivity issue is resolved.
Has anyone experience something like this or provide any clues as to how to resolve?
Look at the sample code in the documentation for the "network" meta tag. We run into the same issue with people writing thick apps on Win Mobile devices. You need to tell the device to connect to the network. The IE browser that comes in the OS does this behind the scenes, as you have noticed, but any other app needs to implement it in the app.