Ahh, you have a 5GHZ router only. thats a pain.
That explains it.
You need (as far as I understand) a second wifi receiver (usb dongle) plugged into the PI set to 2.4Ghz and leave the PI's internal set to 5GHZ and set up a bridge/host/router. I'm not sure how to do this as I don't know about enough about the PI (only just got one!)