what do they mean by "DHCP only"?
This setting is rarely needed any more....and would be used only if your Internet Service Provider (ISP) or a separate DHCP server has supplied the AirPort with a bank of fixed or static IP addresses to use.
But if "DHCP only" is selected, does it try to route between the WAN port and the LAN ports
The first fixed IP address would be used to setup the AirPort to connect using that Static IP address. Call that the WAN IP Address. The other remaining IP addresses would be provided by the AirPort to route to connected devices.
So, let's say that a DHCP server was providing the following IP addresses that you wanted to use:
The first address, 126.96.36.199 would be used as a Static IP address for the AirPort to connect to the network
Then, click the Network tab and select DHCP only and enter the range of IP addresses to be used. So the range would look something like 188.8.131.52 to 184.108.40.206 or higher depending on how many IP addresses the DHCP server was issuing.
So can I use an Aiport to do what I need?
I honestly don't know since I do not understand what you are trying to accomplish.
Anyone know whther routing functionality is disabled in "DHCP only" mode?
In "DHCP only" mode, the AirPort connects using the first fixed IP address that the server provides and it routes the other range of IP addresses to connected devices. In effect, in "DHCP only" mode, the AirPort is a router that does not provide NAT service.
I do not know if that is what you are looking for. But, if you do not want the AirPort to "route" anything.....you would use Bridge Mode. In that setting the AirPort acts like an unmanaged Ethernet switch with the exception that you could use it to set up wireless service if you needed that.
OK, so in "DHCP only" mode routing is enabled.
Yes. As I said, in "DHCP only" mode, the AirPort connects using the first fixed IP address that the server provides and it routes the other range of IP addresses to connected devices. In effect, in "DHCP only" mode, the AirPort is a router that does not provide NAT service.
I wish Apple would make their documentation more complete.
You might want to let Apple know.