After mac os big sur, the security of Apple system is improved, which causes rvictl -s to fail to create a virtual network card.

Solution:

Restart the mac in recovery mode.
1. After booting, press and hold command + r until you enter the boot page
2. Select terminal in the upper left menu bar, type csrutil disable, and then select reboot in the upper left menu bar.
3. After rebooting, go to Security and Privacy, open the small lock in the lower left corner, there is an Apple. The computer will restart automatically.
3. Run rvictl -s device udid again and it will work.