Universal Media Server | Forum

It sounds to me like UMS is NOT on the same subnet as the renderers. It doesn't matter if you can access the web-interface or if shares are visible. All those things use unicast, which easily travels between subnets via a router. The problem is that UPnP relies on MULTIcast, which is a whole different ballgame when it comes to traversing routers.

The only way to check if they're on the same subnet is by actually comparing the IP addresses and subnet masks. If you're not that familiar with subnet "calculations", I'd suggest using an online subnet calculator like for example this: http://www.subnet-calculator.com/

It will show you what range of IP addresses belongs to the subnet defined by an IP address with subnet mask. All other devices must then also have addresses/masks that matches so that they are within the "range" of that subnet.

As long as everything is on the same subnet, the usual suspect is the firewall on the computer running UMS blocking the traffic.