The hell with Synology. I say just go with Roon. 
That might actually be an interesting test. Stand up a Roon server (on a desktop computer, for example). It should reach the NDX2 as an endpoint with no problem. Then point Roon to the NAS as a music file source and see if that works.
You dont need to redact your IPs. Nobody can break in and hack you !
Being circumspect felt like the best course of action - as you can probably tell, networking isnāt exactly in my wheelhouse?! 
Does this mean your network is running multiple DHCP servers?
If your ISP router is providing DHCP you donāt need a NAS providing this service as well.
Possible problems include IP clashes, mismatched gateways and devices with different domains based on what the DHCP scope serves.
For instance all devices on my home BT network respond to names ending ā.homeā
This from SSH on NAS
On your PC desktop what happens if you open a Command Prompt and run following commands:
ping -4 homeserver
nslookup homeserver
I suspect things might be resolved by turning off the DHCP Server package and setting your NAS to get the IP from DHCP and restarting it. Might need to restart networked devices to ensure they get DHCP from router.
looks like DHCP is running on Synology and Router from above screen shots.
Switch off Synology would be my suggestion.
Then do full restart of router
CK
Especially when they are private, local IP range.
Totally agree with others. Run the DHCP server in your router and turn them off everywhere else (I.e. NAS). That could very well be the issue. You can not have multiple DHCP services running on the same LAN.
Restart everything! Otherwise you might have to wait for devices to renew their IP addresses from DHCP before conflicts/mismatches, etc are resolved.
I initially got this from the command prompt - using your ping and nslookup.
Now Iāve stopped the DHCP service on the NAS, performed a full power cycle on; the router, the NDX2, then the NAS. Now I can see the NAS is connected, with a newly appointed IP, running on DHCP from the router.
When I look at the Naim/Focal app now, thereās still no hint of the Synology! It never shows up. Iām getting to the point where Iām wondering if itās just best to negate the Netgear Swtich entirely, and just hard-wire the NAS straight into the rear of the NDX2 - even though itās to the detriment of every other device that actually can connect to the Synology. At least Iāll be able to access the content of the NAS from my NDX2 - which is all I wanted to achieve. I had this working on my old NDX, so I donāt understand whatās so different with this model? 
I also worked through every suggestion from the Synology Knowledge Center link, you kindly provided, My DLNA player cannot detect Synology NAS. What can I do? Nothing in there seemed to improve the situation either, sadly.
Thanks,
Dan
Re Media Server, just a question ā¦. have you indexed your music folders.
( I moved away from Media Server when Illustrate introād Asset for Synology )
And after all these resets and restarts have you reconfirmed that Media Server is running?
Pardon my ignorance if Iām wrong, but isnāt it the case that if you directly connect a NAS (or an USB drive for that matter) to a NDX2, you can put the latter into server mode so that other devices on the network can see the files to play via UPnP?
But if youāre using the NAS for other things I agree thatās a problem. But maybe worth trying just to see if you can get the NDX2 playing files from the NAS.
Maybe time to change the Nas. I think I would give up at your place.
You can put some favourite albums in an USB stick, to connect to your Ndx2. The sound may be even better.
And if you resolve finally this problem, you will receive the medal of patience.
That should work like magic 
Your network is in a better place than when this thread started, but the problem hasnāt been resolved 
Since the Synology doesnāt appear in multiple clients (naim, VLC) we have established the issue must be with the NAS.
My next step would be to open package manager and stop then uninstall Media Server. Reboot NAS and reinstall, setting up afresh. If you want to check what folders are indexed before/after install use Control Panel/Indexing Service.
There are also reports of similar issue where DSM needs a mode 2 reset but that is quite involved. The MediaServer does log to /var/log/packages but you need SSH enabled to view that.
As a last resort I might also try NAS cabled directly into ISP router setting discovery period to something like 10 seconds (resetting to something like 180 after) at Package Center > Media Server > General Settings
There is a trial version of Asset uPnP Server for Synology which you could try installing.
Hi Ian,
Appreciate your advice in this. Iāll work through as much of this as possible today. I agree though, it feels like a NAS-specific issue. Failing that, I may have to raise a ticket with Synology, and see if they can assist in finding a solution.
Thanks Again,
Dan
Have you tried a full reset to factory using the pinhole on the rear panelon the synology?
As a last resort could be worth a try, you can back up any config data for a full restore.
