Thanks for this guide. It also applied to disassembling my older DS214play. Like the DS218+, the DS214play has its outer shell secured by one screw at the rear panel and also has the same ports.
I have an older Synology DS214play and I hoped this guide would mostly apply to that model. The DS214play has one screw on the back panel that secures the outer shell. The guide for the DS218+ contains a rear panel that is more like the DS214play, with one screw and an eSATA port. Still, thanks for the clear instructions and photos.
The red (7 mm) and orange (5 mm) circles at the top right quadrant of the silver panel should be swapped.
The red circle at the bottom left quadrant of the silver panel is around a plastic post, not a screw. It should be around the screw that has an orange circle around it in the same quadrant.
The second 5 mm screw that should be circled in orange is just to the right and slightly lower than the screw that is circled in red in the bottom right quadrant.