If you are having trouble connecting to the NBA 2K15 servers to play MyCAREER, MyTEAM or any other online mode, Gento has discovered a workaround to get online.
Unfortunately, it requires a friend to invite you to a MyTEAM matchup, so if you don't have any friends online, you're stuck. This is confirmed to work on the PlayStation 4, but feel free to try it out on the PC and/or Xbox One and let us know if it worked for you. If you find any other workarounds, please post them here.
This will be a temporary workaround, until 2K fixes the problem.