I have two computers (Comp1 and Comp2)
Comp1 has Oracle VM VirtualBox installed and (Win10).
Comp2 only has Win10
Installed UltraVNC 1.4.3.6 on both computers. (no problem)
Both are on the same local network.
No problem running UltraVNC viewer.
I can control comp2 from comp1 without problem.

But when I try to perform a "file transfer" from Comp1 by right-clicking at the top of UltraVNC Viewer and selecting file transter, (The file transfer button is missing)
the message "The connected VNC Server doesn't support UltraVNC File Transfer!" is shown.

If I try to control Comp1 from Comp2 - Comp1 does not exist (unable to connect)
Is it impossible to run UltraVNC on a computer with WM?
or how to solve this?