Is is possible you may be mistaken as to the cause and your actions to resolve...
I am trying to access https://<ip_address_here>:8080
It seems that my iptables rule for port 443 was gone.
If your ispconfig is running on port 8080, and you're connecting to https://youripordomain:8080
then its not going anywhere near 443.
So opening 443 for that ip address will allow traffic on that port but won't do anything for 8080...
If it wasnt working yesterday and its working now I'd suspect something in between your client and the sever.
Unless of course you do mean 8080 all the way along in your notes and firewall ruleset?
You might want to check out something like firewall builder www.fwbuilder.org
to build and deploy a comprehensive firewall for your needs - you can set it on boot and your ruleset will therefore be permanent.