My Tobii Pro X3-120 doesn't connect or has an unstable connection.

Check the Tobii ProX3-120 USB requirements.

The Tobii Pro X3-120 requires a connection to a powered USB-3 port with the latest drivers.

The port should be able to deliver a 1.9A (10W) current.

To make sure you have the latest USB-3 drivers, download the latest "USB 3.0 eXtensible Host Controller" drivers from the supplier's website. The Windows "check for updates" will likely not give you the latest driver available.

If your computer is not equiped with such a USB port you can use the External Processing Unit for X3-120.