Find the device IP (usually accessible inside firmware menus) and connect to it directly using the "IP" button in the top left menu of the Dirac Live "Select device" screen.
You might also try assigning new IPs to your devices via your router settings menu. Setting a static IPs for the AVR might also help.
Please read your AVR manual to see if there is an option to enable/disable 'RS232' or 'IP control'. You should always have this option enabled to 'IP control'.