Best is to try via wi-fi. But if you're in a crappy area like me where Streamyx often fails when using Cydia ... one option (albeit a little expensive if you don't need it) is to use your telco's EDGE/3G connection. In my case, I often open Cydia using Digi's EDGE without problems. If you still want to try via Streamyx, an option is to try early in the morning as one of the users here had said.