I use a physical SPP 6.0 appliance.
I need to use 2 network interfaces. One for management and one for service.
But I can only configure the X0 interface. Can the X1 interface also be changed?
The X1 I/F was originally used by the virtual session capture module that ran on Safeguard before the acquired Balabit and supplied it as a separate module. Hence you now have the SPP and SPS. At this point the X1 I/F was disabled.
To the best of my knowledge there is no way to use the X1 I/F in the present releases although I did hear a rumor that it was road mapped to re-enable the X1 interface in a future release but I do not know for what purpose. Network segmentation and NIC teaming have both been asked for by various customers.
Your best bet to get a definitive answer would be to raise a case with Support asking for a feature enhancement. They may then be able to share more details with you as they have the relationship with Dev and the Product Management team. They can also log it as either a new enhancement request or add you to the existing request.
Support for use of the X1 interface was added in 6.9. Information can be found in the release notes, One Identity Safeguard for Privileged Passwords 6.9 - Release Notes, and the admin guide.