I just tested the download for this same patch and it seemed to work fine.
In case you still want to know...you can pick out the exact URL being used if you look for it in the newest ST.Protect.managed log file that Protect generates. You may need to enable "All" logging.
It should be found in one of the locations mentioned in the following document, based on version:
I found our content filter was blocking access to Mozilla's FTP site. The logs had what I needed to figure that out, thanks for the instruction.