Does the Synology DS1821+ support 10GbE upgrades?

Regarding the Synology: The DS1821+ ships with only four Gigabit Ethernet ports, but it has a hidden PCIe Gen3 x8 slot that can take a 10GbE network card. For an eight-bay NAS, that upgrade is almost essential because Gigabit becomes a bottleneck with six or eight drives spinning.