If your computers and devices support N wireless get a good N wireless router -- you will still use your DNA-A212 as your ADSL2+ modem, just turn off the wireless and attach the new router to an LAN port. You will have to turn off DHCP in either your current DNA-A212 or the new router, as you only want one DHCP server assigning addresses, but which one you use is up to you.
I would only recommend concurrent dual band if your device adapters support 5GHz, if all are 2.4GHz save the money and go with something like a D-Link DIR-655, which has excellent N 2.4GHz range.
Also, avoid 802.11ac routers as they are too expensive, your devices won't use their features, and the early models out now will soon be obsolete.