iMac to Sony Bravia

I have an iMac running ios 10.6.8 and the latest serviio software. When I start serviio I get an error message 500 which disappears when I click ok. On my Sony Bravia 2013 TV I can see the Serviio icon as a connected device and it says it is connected to my iMac but when I try to open it I get a "server temporarily unavailable" message. I also run serviio on a Toshiba laptop running Windows and don't have any problems. All my media is on the mac so would like to be able to use it. Can you help?