This article covers the issue when you load a page the pictures don't show up.
This covers edge cached traffic, therefore HTTP.
The images are dynamic contents that are fetched from a different site. Edge cache times out trying to get these images. This is usually seen in low bandwidth networks.
Increase the Edge Cache time out:
- Go to Configuration > System > Optimization Edge Cache tab.
- Increase the timeout from the default, 20 seconds and test.