Modern Watchgurad allow downloading of a OpenVPN configuration file from https://your gateway here/sslvpn_logon.shtml that works out of the box.
At least it does for me on Ubuntu 24.04 LTS under KDE, which means I no longer have hardware to test this against.
Also known as the Shrewsoft VPN Manager.
The Shrew Soft VPN Client for Linux and BSD is an IPsec Client for FreeBSD, NetBSD and many Linux based operating systems. This version is distributed under an OSI approved open source license and is hosted in a public subversion repository. It supports most of the features available in the Windows VPN Client version with the exception of those which are not cross platform compatible.
Website: https://www.shrew.net/home
snap install --edge ike-qt-lts or use something like the Ubuntu Software store
Before use, start the service
sudo snap start ike-qt
To open the graphical interface
/snap/bin/ike-qt-lts.qikea
Example : https://github.com/tomchiverton/ike/wiki#basic-start-up-script