"A socket operation was attempted to an unreachable network. Error: 0x80072743"
This error usually means that the Slingplayer can't connect to your Slingbox. I would recommend in trying to connect the Slingbox directly to your router to isolate whether the problem is with the Slingbox or the Powerline Network Adapters. That way you can use a process of elimination to focus on the device which requires troubleshooting.