Download dropping to zero when computer sleeps

I've tried options others posted, however, one way to get around this issue is to repair the game. On the top right there is a question mark or help icon.

Click this icon and 4 options will come up. Click repair and it will scan your files. May take about 5mins or less. I'm using a mac.

After it repairs it will resume from the percent it was at, providing that you did not close the client. Else it will start from fresh again.

Hope this helps