everything worked fine;
yesterday suddenly the problems started to appear
on the web client there's often a message "we are having trouble playing this video. check your playback setup. sometimes there's no sound. sometimes it says that server is not powerful enough or something like that. problems more often are happening when resuming playback rather than starting from the beginning.
ipad client sometimes quits just after starting, sometimes it plays, but no sound. desktop client on the same box as the server seems to be working fine.
server 0.9.11.12 on Mac mini. connected over the wire to a Drobo NAS on the same network. files which do not work well are usually blu ray backups in MKV format, sound is usually lossless FLAC
I restarted the server few times, doesn't seem to help. Not sure where even to start looking to troubleshoot this.