The Ip pool and scope has all stayed the same with plenty of spare IPs.
We had the APs on Ip reservations but we have tried removing the lease and reservation but it does the same. We have tried resetting the APs by holding the reset button for 12 seconds and it recommissioning itself. Tried leaving it to DHCP and setting it to a static IP
Did you change the ip address of the DHCP server? If so and have vlans setup you may need to change the ip helper settings on the Vlan interface on the switch doing the vlan routing. also may need to approve the dhcp server.
Authorizing the DHCP Server
A DHCP server can be authorized through the DHCP management console by an member of the Enterprise Admins group. To authorize a DHCP server, perform the following steps:
Click Start, point to Programs, Administrative Tools, and click DHCP.
Within the DHCP management console, right-click the DHCP server and click Authorize.
Once authorized, the DHCP server can respond to client requests for IP address parameters.