Are there any reasonably straightforward open source VPN servers compatible with Apple’s clients? For cloud and VPS setups, I always end up mucking around with OpenVPN/Tunnelblick.
The strongSwan configuration generated by pfSense works out of the box with macOS and iOS IKEv2 support in its default config. This has quickly become my VPN solution of choice as it works without a third party app, it’s extremely quick to connect and the connection is super stable.
I found SoftEther easy to install on a bargain VPS. Supposedly it has much better throughput than OpenVPN, but I am not certain that it has had enough scrutiny to insure that it as worthy of trust as OpenVPN. Since I don't really know anything about my bargain VPS provider either, I am not using it for great privacy, I just turned it on when I imagined there was suspicious throttling, which probably didn't exist anyway. (Getting the latest cable modem model from Comcast seemed to solve more of my latency issues than opening a VPN tunnel ever did.)
More specifically, it is L2TP over IPSec on MacOS and iOS devices.
I tried the OSX VPN stuff and gave up really quickly. It all just felt really clunky, without much control.
Tunnelblick and http://www.pivpn.io/ work great. PiVPN targets Pi installations, but I found it works just fine on any modern ubuntu install. The cli tools to generate / revoke configs are very easy to use.
> straightforward open source VPN servers compatible with Apple’s clients
I wish there were so that I can have one for iOS, but I've been using OpenVPN easily since long enough on macOS that the alternatives always seem terribly cumbersome and brittle.
I've been meaning to try tinc since forever, but it won't integrate with Apple clients either.
Strongswan (Linux and FreeBSD) and iked (OpenBSD), for use with native Apple's IKEv2 clients. Don't try to use IKEv1 (1998, isakmp), its broken and old. And Apple does not provide native support for OpenVPN protocol.