A host networking device networking interface is automatically configured. The interface is initially configured to operate in a single-link mode in which multiple network communication lanes of the interface cooperatively provide a single communication link. If a signal is not present on any communication lane, then the interface is configured to operate in a multiple-link mode in which each lane provides a separate and different communication link, and is operated in the multiple-link mode. If a signal is present on every communication lane, and if the single communication link has been established with another networking device over all the lanes, then the interface is operated in the single-link mode. If a signal is present on every communication lane, but if the single communication link has not been established over all the lanes, then the interface is configured to operate in the multiple-link mode and is operated in the multiple-link mode.