I have 2 units - DIR 655 with the same problem of restarts then failure to reconnect.
HW A3
FW 1.10 (shipped with) and 1.11 (upgraded).
It appears that it also has a problem with N mode as g devices do reattach ok, but not N mode.
I have had 1 RMA already to try and fix it, now both are on the blink (2 different locations with different network configs but the same disconnections...).
To change the network ssid and settings all the time is crazy, every now and again, but really that is a big problem if it is being done several times a day,
Dlink is there a solution on the horizon?