When both IPv4 and IPv6 are enabled, the first few connection attempts fail, but everything works fine after that.
Here's what happens when you use Radius authentication:
SMA1000: Enabling both IPv4 and IPv6 causes the first few connection attempts to fail, but then everything works fine on win10/11 for the network interface
This will be addressed and fixed in the upcoming Ver-12.4.2 March Official hotfixes. Please use the most recent Connect Tunnel client, version 12.4.2-564 or higher.
Please contact technical support if you need a developer CT client.