Have you tried uploading your catalog, images or video files and the upload failed?
It's possible that your computer is going to sleep and stopping the upload, especially if it's a lot of data you're trying to send to us.
Here's how to prevent your computer from going to sleep on a Mac:
1. Open your System Preferences.
2. Click on the lightbulb "Energy Saver" in the Hardware section.
3. Move the slider all the way to the right to "Never."
Exit your System Preferences and start your upload without worrying about it stopping mid-transfer.