Since the original script l2tp_setup.sh not longer work any more. I create a new script, named IKEv2_setup.sh, which do the similar thing: setup an IKEv2 VPN server with one key.
Please refer to How to Set Up an IKEv2 VPN Server with StrongSwan on Ubuntu 22.04 for technical details.
General speaking, you can run below script on your ubuntu 22.04 server to setup IKEv2 VPN server:
$ cd ~
$ wget https://raw.githubusercontent.com/kamidox/One-Key-L2TP-IKEV2-Setup/master/IKEv2_setup.sh
$ sudo chmod a+x IKEv2_setup.sh
$ ./IKEv2_setup.sh
echo "#################################"
echo "What do you want to do:"
echo "1) Setup IKEv2 server"
echo "2) Add an account"
echo "#################################"
Choose 1 to setup server. Choose 2 to add a vpn account.
After that, jump to Step 7 — Testing the VPN Connection on Windows, macOS, Ubuntu, iOS, and Android, verify your VPN server on your client devices.