Cannot connect to L2TP/IPSec VPN

I’m running OS Tumbleweed KDE, trying to connect to an L2TP/IPSec VPN, and I keep getting the message “Starting the service providing the VPN failed.” This is being done with Plasma 5 Network Manager, and the error only occurs if I have IPSec enabled.
I have attempted to use the Yast2-VPN module, but it doesn’t seem have have any features (i.e. using a user name, password, etc.).

I just need to connect to an L2TP/IPSec VPN, and I am having the most difficult time. Most things on Linux come fairly easily to me, but come on, this is tougher than a bloody Macintosh.

What is the reference you’re using to set up an L2TP VPN?
So, for instance IPv6 now has integrated L2TP.

You also need to describe specifically the method you’re using to exchange certificates/keys.

TSU

Hi, the VPN is set up using a Zyxel Zywall, and it’s a pre-shared key encryption, with a user name and password. I’m fairly new to VPNs, so excuse my ignorance.

Unless someone here just happens to use that Zyxel Zywall, you’ll likely have to ask in a forum, mailing list or IRC supporting that specific software. The way it sets up its VPN connection can be a custom procedure. Also, FYI you may also need to specify that you’re setting up a beachhead to beachhead or beachhead to client connection.

You’ll also need to say whether your openSUSE is a remote client or a host in the network behind the Zyxel.

Have you checked whether there is Zyxel documentation that steps you through a VPN setup?

TSU