This is strange! When I log into 5D with my wi-fi in home (clear network) on my iphone 4 (ios7) it works fine. However, when I roam and try to log-in using just my Sprint internet the log-in says my information is incorrect--which it is not! Is Sprint doing some funny business? So far 5D live help has been no help identifying the issue, frankly, I am not sure they even believe me.
I have sprint and I never had a log in issue. I don't use the LTE feature on my phone. I make sure it stays on 3G CDMA at all times. I never have a great internet connection in the area for some reason. Sprint told me to try 3G CDMA 100% of the time. Maybe that might help you out? I just use the regular browser that came with the phone. Samsung Galaxy s3