Synology DiskStation DS2419+ Hardware Installation Manual page 14

3 Remove the PCIe expansion slot shield:
a Reposition your DiskStation so that the top will be facing your body, with drive trays on the right side.
b Pull the clip above the PCIe expansion slot shield in the direction as illustrated below.
c Remove the shield.
4 Install the network interface card:
a Align the card's connectors with the PCIe expansion slot.
14 Chapter 2: Hardware Setup