I have the same problem sometimes. I have not really an idea, but it only happens if I play a video through MC in the Living Room on my Media Renderer cotrolled by JRemote. If I then in parrallel use the Apple Internet Browser, then JRemote sometime looses the connection.
It never happens if I use JRemote to control the Workstation.
Network Architecture is:
WS (MC + Server, Docs, IMG;Audio;Video); File Server (Video:Movies & Series from BD, DVD)->Ethernet->Router->WLAN->Repeater->Ethernet->Switch->Ethernet->Media Renderer (MC Client) | All Mesh Metwork, WiFi 5
The problem is that you can not have a deciated Wifi Network for Streaming and a 2nd WiFi Network for CTRL, Browsing etc. I have no solution to that.