I had some VPN connections set up working quite nicely. Now, they're not. I'm using Kubuntu 20.04 and it uses the new OpenVPN 3 client. I would like to install OpenVPN 2.X to see whether that get's my VPN connections working. How do I install OpenVPN 2.X on Kubuntu to test it? If it works, how do I stop Kubuntu upgrading to OpenVPN 3?