linux – Easiest way to set up a “proper” VPN on a CentOS server, allowing an Ubuntu or Windows client to connect to it

I am using Ubuntu at home. I have a server in the US with CentOS.

With my system administrator days long gone (about 25 years ago), the question is: what’s the easiest, least painful way to make a CentOS Linux server act as a full VPN, and then route ALL of my traffic to that US server?

When I look online, I find plenty of guides for Squid (not what I want), more about Socks (again, not what I want since I want ALL traffic to go through the VPN), and difficult guides on how to set a VPN on a server. Are there any turnkey-ish solutions out there? Something I can use with the standard Ubuntu UI (or Windows’ UI for VPNs), which allows me to add a VPN?

(If you wondered, in the last 25 years I’ve been a tech journalist and software engineer, rather than system administrator)