Thank you, TheWitness & gunrunnerjohn. That explains a lot.
I have to be fair, for the price, it does the job. When I say job, I mean backup, maybe streaming audio, but not video.
In Wireless connection, my Media Player refuse to play any video files from DNS-323 most of the time. I may get luck one time or two, but that's about it. I am sure wired connection will change the situation, but most of us are not using wired connection anymore.
Anyway, like I said, I just keep backups on it now.
Happy New Year, guys!