Hello NateHevens
Welcome to Microsoft Community.
Regarding to your information I assume that you want allow the website through the Windows Firewall.
You can try to create the rule about this website.
Search the CMD, then run as administrator.
Use nslookup www.xxxx.com****get the website ip you want visit.
Search "Windows Defender Firewall with Advanced Security" Click it.
Create the rule->Custom->All programs->Any
Add the ip you get before.
Allow the connection.
Add this rule in Inbound Rules and Outbound Rules.
Try visit the webiste.
You can also try to reset the firewall or use the security DNS server.
If there is anything not clear, please do not hesitate to let me know.
Best Regards,
Tommy-MSFT | Microsoft Community Support Specialist