Routers and multicast discovery

[tboooe]

I have two instances of Minimsever running on two different wireless routers. One works all the time while the other is a little unreliable.

The reliable instance is connected directly to my Asus Nighthawk R7000. The PC is running Windows 7.
The unreliable instance is connected directly to my Dlink DAP-1650 Wireless Access Point (acting as wireless bridge). The PC is running Server Essentials with Audiophile Optimizer and Fidelizer.

The issue is that sometimes Minimserver will not show up in the Control Point. I know the wireless connection is OK because the renderer running on that same PC shows up fine in the control point. The only way to get Minimserver to show up is to unplug and replug the ethernet cable. There is no IGMP setting to change.