Jin,
I just wanted to say thank you for giving me some ideas that are helping me re-think my approach to make this as painless as possible for Alex. If I understood your post correctly, I agree that one of the problems is he is no longer on the same subnet as the router and I believe this is because we disabled DHCP. While we can solve this problem by going static, I think the best approach here is to simply disable DHCP as the last step to avoid this issue altogether.
Close. There are two possible scenarios on integrating routing equipment out of the box:
1. Is they are BOTH on the same subnet.
A. They either have the same default management IP (collision)
B. They have separate management IP (OK)
C. They have DHCP turned on
1. Possible same scope distribution (possible client collision)
2. They have complimentary scopes allotments (OK)
The first thing to always do is get the vendor documentation together on the OOB defaults and plan accordingly.
If on separate subnets you simply statically assign two IP address to the network card (multi-homed adapter) and connect the non-routing device to the routing device, plug in your computer, adjust the non-routing device to be compatible on the piece that needs to perform the routing and disable it's DHCP server. Layer two doesn't care how many subnets you have so no problem having two routers plugged into a common LAN port.
If you pick up two devices that have the same subnet and therefore managment IP you will configure a static on the computers adapter. Connect to the device to be configured as an AP and simple change it's IP and disable DHCP. Then plug into the LAN on the routing device.
The point behind having the computer statically assigned with addressing is if you don't remember if you applied settings you can still try the old address to get back to the router you need to modify.
The issue with DHCP and turning it off last is that your computer isn't going to pull two difference DHCP assignments. It is imperative that you statically assign and potentially multi-home the adapter. Trust me it is easier in the long run and you are not left scratching your head on which network assignment you leased.
With static addressing you
know what networks you are on. In Cisco parlance you are on a multi-armed (as in an octopus) configuration.