CDN network appears down

Yesterday afternoon it was indicated that a customer’s website was taking an exceptionally long time to load. Looking into it, this was the case as it wouldn’t load images and took a massaive amount to load a basic structure or weird listing of links in place of the designed page.
After looking at issues like potential malware and other concerns, I turned off the CDN and the pages started loading again properly. This was the case for (7) pages that I maintain.
After doing this I ran the “test before enabling” link and it returns a blue screen “Error – 504 Gateway Timeout – Webdesign & Development by Shift8”