Similar thing is happening to my 323 and I got a DIR 655. I have been using it lots for the last year with no problem at all and now, all of a sudden, it will not allow me to connect most of the time. Every once in a while I'll get lucky and I'll be able to get in for about 1min before it disconnects. I have everything connected through a switch (like the previous advice) so I tried resetting the switch with no luck. I also tried another switch with the same results. Tried accessing through FTP, no luck either. Lights are flashing as per normal for both hard drives and the network drive. When I use the search utility, it only finds my other NAS drive (which I have been using for a year with no problems or conflict too) MyBook. Weird. It won't map the drive obviously. I inspected the hard drives and they had no apparent damage. I'll try them individually on a external hard drive enclosure, hopefully they both work individually like yours so at least I'll be able to recover my 1Tb of music and movies!