CDN Routing issues with VPS getting blocked
I've currently setup a CDN using Stackpath, and after I had my whole Wordpress VPS site under their CDN + WAF - everything was working great! However about 5 days later, I started noticing random images, css, and js assets not loading. On one browser, one image would not load. Open that same page up in another browser - a different image would not load, but that first image would load. So I contacted Stackpath and it turns out that when my site is under the CDN + WAF security, my VPS would intermittently block communications with their servers. I've added all their IP's to my iptable so that the firewall lets them through, but something is still not letting them through 100%. They had the same issue with their curl test and that its connection would work partially, but then would get connection refused error. So is something on my end throttling their servers? If so how would I check that? Or what else could be the issue?
As a side note - right now the site is just serving up static assets from their CDN just fine, but ideally I would like to take advantage of the WAF.
Thanks in advance for any troubleshooting help with the cdn.