For some time now there has been a bug in the DATA BANDWIDTH selection in options that has caused problems for people downloading updates.
It seems that if you select a data speed limit while in the DATA section in OPTIONS then that data speed limit will be enforced when updating the sim. As you cannot enter the sim to make changes to your settings until the download is complete, this can cause extremely slow downloads even if the user has fast internet.
In discussion with other members, we suggested a selection in the installer that would give the option of overriding the data speed limit selected in-game while doing updates.
This would also apply to the DATA LIMIT as having a cap on your total data will stop your download if that cap is reached.