A serial bus repeater includes first and second ports adapted to be coupled to respective devices. A first termination resistor network couples to the first port. A second termination resistor network couples to the second port. A squelch detect circuit couples to the first bus port and is configured to detect activity on the first bus and to generate a squelch signal responsive to detection of activity on the first port. A first state machine is configured to: determine an elapsed time during which the squelch signal indicates activity on the first port; determine that the elapsed time exceeds a first threshold; and, responsive to the determination that the elapsed time exceeds the first threshold, assert configuration signals to reconfigure the first and second termination resistor networks.