The Synology DS1520+ packs four Gigabit ports with link aggregation

Most NAS units in this class give you two Ethernet ports. Synology gave the DS1520+ four 1GbE RJ-45 LAN ports with link aggregation and failover support. Bond them together and you can push up to 4GbE aggregate throughput — useful if multiple people are hitting the NAS simultaneously, even if no single connection breaks the 1GbE ceiling.