This will be of great immediate benefit since 802.11ac is still gaining a foothold, but 5GHz 802.11n is in nearly all phones, tablets and laptops of the last few years.
Make sure "Use DHCP Server:" is enabled, then look at the information under DHCP pool.
Obviously, this differs depending on what you're trying to connect with (PC, laptop, PDA, games console, etc), but below are some common things that you'll need to do: That should be enough to get you going.
Wi-fi in the UK can use one of 13 different channels.
Many have found this setting causes repeated drop outs.
Apparently, the BT Help Desk actually recommend you use channel 9-11 for best connectivity using the manual setting.
These are faster than anything we have seen excluding the breakaway performance of the EA6900.