USB Tethering is not working

I’m facing an issue with my Herelink controller (HX4-06211). USB tethering is visible but permanently greyed out, and when I connect it to a Windows PC, it only charges—no MTP, ADB, or RNDIS device is detected.

What I’ve tried:

  • Multiple data cables and USB ports (USB 2.0/3.0)

  • Different Windows PCs

  • Factory reset

  • Enabled USB Debugging

  • Enabled RNDIS in Developer Options

  • Rebooted both devices

Problem:

  • PC does not detect any USB device at all

  • USB tethering remains greyed out