Can TeamViewer be used within a local network (LAN) only?
You can establish Remote control sessions on your local network directly by using IP addresses or computer names. By default this feature is deactivated because software firewalls may open an acceptance dialog when configured this way.
To activate the LAN mode in TeamViewer full version and Host module:
In the menu click on Extras and then on Options
On the General tab activate Accept incoming LAN connections
When selecting accept exclusively it will display the IP-address of the computer in the ID-field.
A connection can now be established using the IP-address or alternatively using the host name.