NetworkManager attempts to keep an active network connection available at all times.?BR The point of NetworkManager is to make networking configuration and setup as painless and automatic as possible. If using DHCP, NetworkManager is intended to replace default routes, obtain IP addresses from a DHCP server, and change nameservers whenever it sees fit. In effect, the goal of NetworkManager is to make networking Just Work. If you have special needs, we'd like to hear about them, but understand that NetworkManager is not intended to serve the needs of all users.




Make sure you read the fine manual


How do I configure static IP adress (for a server, etc) ?
configure /etc/network/interfaces
Why can't I see NetworkManager with my new user account ?

make sure allow human users are in the group netdev (see /usr/share/doc/network-manager-gnome/README.Debian ).