Provided are a computer program product, system, and method for using an out-of-band network to coordinate a first node reconfiguring a bus interface port used by a second node to communicate on a bus. The first node configures the bus to enable the second node to link to the bus. The second node sends a join request to the first node over an out-of-band network separate from the bus in response to determining that the second node cannot join the bus. The first node reconfigures the bus to enable the second node to communicate on the bus in response to receiving the join request from the second node over the out-of-band network.