No audio devices found within a minute after restart


Roon looses the connection to all my audio devices within a minute after the roon server is started. They all reappear after a shutdown and restart of roon and then disappear again within a short period of time. Sometimes they reappear without a restart only to disappear later on again.

I am running the following:
roon version 1.2 build 161 64 bit on a headless Mac mini, OS X 10.8.5, 4GB Ram, firewall off, wired Ethernet connection to an Actiontec router, music stored on external FireWire hard drive connected to Mac mini. I am also using Tidal, in total my Library has 760 albums.
My control points are various IPads and iPhones, main control is an iPad Pro running roon 1.2, build 162, 64 bit
My audio devices are a Naim Mu-so (via airplay) with wired Ethernet connection, a raspberry Pi running roon bridge, version 1.0 build 38, with wired Ethernet connection to Actiontec router and a libratone ZIPP speaker (via airplay) and an Apple TV, 3rd generation(via airplay) wired Ethernet connection.

Help would be much appreciated