These instructions are largely the same as the ones in the official PDF-file that goes through the migration progress, but with the (hopefully) helpful addition that the the incorrect command is corrected and the other commands are copy:able as-is.
Turn off the VPN service in the Server app. (If visible. For me it was not.)
Make sure you are in the
wheel group. I followed these steps (link )
Open Terminal (where the rest of the instructions will be executed) and go to the appropriate directory with:
Create an empty file called
vpn.ppp.l2tp.plist in current directory with:
sudo touch vpn.ppp.l2tp.plist
Set the right owner for the file with
sudo chown root:wheel ./vpn.ppp.l2tp.plist
Open the file with
nano (to avoid problems with saving that can occur if you use TextEdit or similar):
sudo nano vpn.ppp.l2tp.plist
Copy paste the content below into
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
Save with changes by pressing Control + o, confirm file name with Enter and close nano with Control + q.
Load your new file by running:
sudo launchctl load -w ./vpn.ppp.l2tp.plist
launchctl print system/vpn.ppp.l2tp
These steps worked for me. Hopefully they can help for someone else that, like me, struggled to get the VPN feature up and running again after macOS Mojave update.
The official PDF guide (mentioned above) has some additional information about "Ongoing management":
Settings can be changed after vpnd is configured by editing the
com.apple.RemoteAccessServers.plist file. Refer to the vpnd (5) man page for details on the configuration format. After changes are made, you can have the service reread the configuration file by executing the command
sudo killall -HUP vpnd.