Can't Access NAS By Name on a Mac

I've been reading various posts that seem related to my problem, but I haven't come upon one that is exactly what I need. I'm a bit of a newbie to this stuff, so I could be missing something, but hopefully someone can help me...

MY SETUP

• In the basement, I have a Verizon FIOS modem plugged into a Verizon FIOS g1100 router that has its Wifi disabled. This g1100 is used to:
  1. Provide MOCA over COAX to various parts of the house;
  2. Connect a Synology NAS that resides in the basement; and
  3. Feed an ethernet line to an office upstairs
• In the office upstairs, I have an Orbi router set up providing wifi to 2 satellites, as well as ethernet to a desktop computer

MY ISSUE

• I can access the NAS via its IP address in a browser (http://192.168.1.151:500)
• I can connect to the NAS from my Mac's Finder via its IP address (smb://192.168.1.151)
• But I can't access the NAS via its server name, either in a browser or through the Finder

Before I introduced the Orbi into my setup, the NAS server name would appear in my Mac Finder sidebar and was accessible via its name, but this is no longer the case.

WHAT I'VE TRIED

• I know having 2 routers is not ideal, but i'd like to preserve the MOCA feed downstairs. I tried to put the g1100 into bridge mode, but that hosed my entire setup (I must've made a mistake), so I'm gun-shy of trying that again.
• The Orbi IP address is 10.0.0.1, which I've read is a sign I'm running "double NAT", but I'm not sure that is the source of my problem. I've read the IP address of one should be changed to be within range of the other, but I'm not sure where in the Synology or Orbi GUIs I'm supposed to do that.

Any pointers on which of these issues might be the root cause, and what the recommended solution would be so I can access my NAS by its name? I'm planning on adding another NAS in the basement, so it would be ideal to reference them by name rather than IP address.

Thanks!