I use a real vnc viewer to connect to my host machine. The host machine has Linux in the GUI mode. I would like to switch between the GUI and the console mode, however the key Ctrl+Alt+F1 opens up my local graphics control panel. I tried using the Menu key F8 as well but it is also not working. The same problem occurs for tigervnc as well.
VNC server is an X window server and it does not serve the text consoles. So, even if you send the
Ctrl-Alt-F1 combination (there are options at the viewers menu to send some special key combinations), it will not be treated as you expect.
ssh or other kind of terminal connection to get terminal access.