Nicholas, not to be impolite, but I think you’re asking the same question in a different way that was already answered previously;
Just to reiterate the main points from that thread;
- dCS explicitly recommends that you do not do this, and they will not provide any support to get it working that way
- Even if you get it working, you’re not going to experience any sonic benefit from doing so
- You’re going to complicate access for Mosaic Control
Points 2., and 3. are from my own personal experience of doing exactly what you’re trying to do. Additionally, if you’re trying to avoid a network switch in-between because you think it’ll be somehow less “noisy”, a typical NAS is far worse! Connecting it directly back-to-back with your NBR is a bad idea. 
That said, while nobody can provide you with a “guarantee” you can get it working, if you know what you’re doing and pick the right Synology NAS models, its quite trivial to get it working back-to-back with an NBR because many Synology NASes support dual Ethernet with Routing/Virtual switching, and DHCP server functionality. See the Synology Networking section KB;