A network bridge comprising two ports for connection to two networks, a spanning tree controller and a wireless bridge link controller for each port. The ports employ an adaptive modulation technique. The wireless bridge link controller is connected to the port to exchange physical layer information with said port. When the port detects a change of its PHY mode, it sets the path cost of the link to a value configured for the new PHY mode and forces the bridge to recalculate its spanning tree. The wireless bridge link controller is also connected to the spanning tree controller. If the bridge detects that it has not received BPDUs for a certain time period and the timer will expire soon, the bridge forces the port, via the wireless bridge link controller, to use a more robust PHY mode.