I feel everyone's pain here.
I am using a DIR-628 with the latest firmware (1.22) and Shareport (1.10) software. 
Of course, the printer is useable for about a day, then ALL networked computer "see" the printer (Brother HL-2140 laser) but attempting to connect to it, just tries, then returns to "available" status.  FRUSTRATING.
Resetting the router is a pain in the u-know-what, and not always an option.  
I have teens in the house, monitored by SecureSpot for their internet time and habits.  Resetting the DIR-628 results in resetting their allotted time for the internet also.  Unacceptable!  Plus the password on the router is not shared hence a reboot is only available through myself and I am not always available when the kids need to print.
I have tried everything and am getting frustrated.  Looking at the other angry messages here, I do not see any solution.  
I am tempted to sell my DIR-628 (reluctantly, but I have no choice) and get something else.  Preferably with a "network addressable" USB port.  Wouldn't THAT be nice?
Could SOMEONE please sort this out soon.