I have a DIR-655, Hardware version A3, firmware version 1.21 which, although it allows me to connect to the Interwarbs, has a few non-trivial issues...
a) I cannot save any settings. For example, when I try to update the time and click "save settings," the connection times out. When I reload the page, I get a message saying "Please wait... The gateway is currently measuring your network connection. Accessing this web page might have an effect on the measurement. This page will refresh shortly.", after which the router appears to reboot to the login screen -- no settings saved. I cannot engage wireless connectivity for the same reasons... changes in settings won't save.
b) I cannot upgrade firmware. I tried to upgrade the firmware to 1.33NA, hoping this would help, but although the upgrade process appears to conclude successfully, the router's login screen shows me I'm still at 1.21. In other words, the firmware upgrade completely bails. Tried it numerous times with the same result. BTW, when I click on "Check online now for the latest firmware version," the router reports that the firmware version already installed (1.21) is the latest version!
c) I appear to be dropping packets on the LAN side of the house, in both Windows and Linux. For example, since I last restarted the router, 10 minutes ago, the router's statistics show that 3 transmission (Tx) packets have been dropped.
HELP!