Could the opening or closing of any of these ports be involved in an intermittent 8008 error in attempting to download iTunes movies to my Mac?

I've been working on an issue with two Macs and a PC with trying to download movies from iTunes, and the downloads were consistently stopping at about 1/3 of the way through the dowload, with error 8008. When troubleshooting with the ISP in real time, watching the downloads, finally some of the movies downloaded, and others continued to stop, now at either the 1/3 or 2/3 of the data, still with error 8008. I'm wondering if any of these ports not being open could be involved with this issue.