I know this is an old thread, but I've been struggling with something similar with the ver B1 F/W 2.02NA product.
My IOGear USB to 802.11B print server would not connect to this router configured with the same WEP settings as my old Belkin 802.11G router.
My initial configuration was this:
Primary 2.4GHz SSID = B/G/N WPA
Primary 5GHz SSID = A/N WPA
Guest 2.4GHz SSID = WEP
I tried the above setup both with the DIR-825 configured as a router and an AP (DHCP off / no wire to WAN port).
Two problems observed:
1) The printer could not connect to this configuration, but any laptop could.
2) I also found that any device connected in N mode would lose communication with the network (not wireless connection) a few minutes after association. This was easily reproducible by trying to copy a file from a network share through windows explorer. A few bytes would copy, then stop. The connection was fine, but you'd no longer be able to ping the router. Computer connected with G had no problem with this same configuration.
I finally found that the IOGear Wireless B device would connect when the Primary SSID was set to WEP instead of the Guest Zone. So I changed the configuration to this:
Primary 2.4GHz SSID = B/G/N WEP
Primary 5GHz SSID = A/N WPA
Guest 2.4GHz SSID = WPA
Now the IOGear / printer connects with no problem. However issue #2 persists. I've read in some places that 802.11N does not support WEP. If I remove the WEP configuration, my N devices work properly. But then I have no printer. It's also interesting that other routers I use and that work properly with multiple SSIDs would have the WPA SSID available on B/G/N and the WEP SSID available only on B/G. Where as the DIR-825 shows the WEP SSID on B/G/N.
By the way, I should note that the N connection issues are the same regardless of the client device used. It's easily reproducible even with a DWA-160 (ver B1) when connecting on 2.4GHz band.
If anyone knows how to entice D-Link to correct this, please let me know. I'd be more than happy to provide detailed, reproducible use cases.