Here is a recent thread that should give you plenty of information to get going.
On this screen, you have to specify either hostname or IP address of the destination SoftEther VPN Server. You also have to enter the user-name, password and secret (pre-shared key) on the iOS screen.
The 'hostname or IP address of the destination SoftEther VPN server' would be a device on my home network? I have a cable modem from Arris/Motorola, I don't see an option like this anywhere on it's setup pages. I need to buy another device? If so, what?
Would it be best to continue letting the cable modem be the DHCP? Or should I turn it off there and let this new router be the DHCP?
Sorry for all the questions, I just don't want to buy something that won't work.