https://qiita.com/tkyonezu/items/00311e2285366984891c
これどうりにやってみたら
5番目とこで詰まった
systemctl start vpnserver.service
systemctl enable vpnserver.service

エラーメッセージは
pi@raspberrypi:/usr/lib/systemd/system $ sudo systemctl start vpnserver.service
Job for vpnserver.service failed because the control process exited with error code.
See "systemctl status vpnserver.service" and "journalctl -xe" for details.







(糞スレとは言わないでください)