Hi,
So the AP (access point) is connected to port 20 with VLAN 1300 and gets the correct IP. The other devices connected to the switch also get the IP. The issue is when the clients connect to the AP, then they do not get the IP. Is that correct? The AP obtains the IP address and uses Switch -> RUT as a gateway. If I understood your question correctly, the clients connecting to AP should be on a different network. If so, is DHCP enabled on the AP? What are the configurations on the AP? Would it be possible for you to get a TCP dump from the AP to see the flow of DHCP requests?
Kind Regards,
Andzej