If the U-706 is a generic industrial controller, it may output raw data that games or software don't understand. You may need mapping software:
Check for faulty cables, as this is a common cause for "Device Not Recognized" errors in older hardware. Once recognized, you can verify the "U-706" performance: u-706 joystick driver
If you can provide the (from Device Manager), I can help identify the actual chipset and confirm driver status. If the U-706 is a generic industrial controller,
Most "U-706" joysticks use the native Windows HID driver. If the device is not recognized, follow these steps: Open Device Manager . u-706 joystick driver