I am running 4.5 and do not have a TCP selection under Options > Advanced Options. I have an unlimited data plan. My device will only connect using the built-in browser. When I try to use Opera mini or any other device that needs internet connectivity, it fails to connect.
Are you sure your data plan is enabled correctly?
When you check at the top does it say "3G" or "3g" (not the upper/lower case "g")
If your not on a BIS data plan the "G" will be lowercase.
If that is the case, try rebooting the device so that the profile kicks in