The Filetypes preference is set to stream AAC files as Native, which should be OK for my players. I tried disabling the Native setting and also the FLAC transcode so it should stream AAC as MP3, but still no sound.
Also, weirdly, when Squeezebox finishes playing an AAC files it replays the same song instead of moving onto the next song in the queue. Is there something wrong with my AAC files? In another player they are classified as AAC (MP4a, CBR).