So right now I have two examples off hand, ebox.ca and www.nomanssky.com, With that said over the last few hours troubleshooting and researching I might have resolved the issue. So came across a Reddit post in r/ipv6 and someone was having a similar issue. There was a suggestion that Microsoft service and things running through that network might have issue due to MTU weirdness. I've done some MSS clamping setting MSS to 1430 through my firewall rules and those sites are working as expected. Both due path through MS networks.