I have a 624+ - it randomly drops the network - D-Link said there is nothing wrong with it
Also have a D-Link 300G+ modem which while it's ok, is a bit odd in that it has an "Accounts Management" page - where it can only store a single account

which must be deleted before you can edit/add a new account
Both are on the latest firmwares as well.
looking for some replacements now.