Timing, Timing and Timing
Based on own experience in a much different employment situation, three things that semi-work:
(1) Certain times of day/days of the calendar week are less busy. Late night/early morning weekends in the Western Hemisphere are most likely, though not guaranteed. There also seems to be a "supper gap" early evening in (approximately) Central Standard Time which can be exploited, but not every day. After an N3V service pack update when everyone's trying to download it *and* re-downloading their content because installing it disabled their databases, you may be out of luck for a week or more.
(2) Once you get a live connection, work it! Put a large item (multi-megabytes) at the top of your CMP download list. When you finally get a connection, pick all the small stuff (and large stuff) you wanted while it's downloading. Your connection will remain live until the last thing comes down unless you have physical connection problems. If for any reason you *do* lose your connection, try to reconnect at once, several times. Oddly, when you reconnect you often get a much better download speed. I don't know why.
(3) While downloading, you may get red-banner error messages at the bottom of the CMP screen (I'm using CMP2.0, your appearance may differ). This is scary because the red banner remains after its message is delivered... but check the download window, your connection is probably still live and working. Don't panic! Just click on the red message and continue: it goes away and the download contintues.