In some scenarios, most commonly with Synology, the NAS operating system isn't presenting the Asset configuration link properly and Asset configuration cannot be trivially accessed.
Note that you can NOT access Asset UPnP configuration over the internet. Your machine accessing Asset configuration must be on the same local network as your Asset instance.
Short version
Go to http://[ip]:45537 - where [ip] is the local area network IP address of your machine running Asset.
The rest of this document deals with finding your NAS IP address in every possible scenario so you can stop reading if you know it.
Synology NAS
Control Panel / Network / Network Interface / look for x.x.x.x line in LAN record, then open it as: http://x.x.x.x:45537
If your computer runs Windows
Windows Explorer, click "Network" in the left pane, locate Asset UPnP under Media Devices, right-click, choose "View device webpage". This will take you directly to Asset configuration page.
If your computer is a Mac
I made a simple program for finding running Assets on your network:
Note that you can NOT access Asset UPnP configuration over the internet. Your machine accessing Asset configuration must be on the same local network as your Asset instance.
Short version
Go to http://[ip]:45537 - where [ip] is the local area network IP address of your machine running Asset.
The rest of this document deals with finding your NAS IP address in every possible scenario so you can stop reading if you know it.
Synology NAS
Control Panel / Network / Network Interface / look for x.x.x.x line in LAN record, then open it as: http://x.x.x.x:45537
If your computer runs Windows
Windows Explorer, click "Network" in the left pane, locate Asset UPnP under Media Devices, right-click, choose "View device webpage". This will take you directly to Asset configuration page.
If your computer is a Mac
I made a simple program for finding running Assets on your network: