IPMI has a failover function. When booting the system, IPMI checks for a link connection on the dedicated IPMI port. When there is none, it will try to establish a connection on the first lan port. So make sure there is a working connection on the dedicated port when IPMI initializes. When you have a working connection on the dedicated IPMI port, then shut down the system, remove AC power for ~1 minute, and boot the system again.