Problem with converting router into an access point

Hello guys!

We have a D-Link DI-524 router connected to our modem. We purchased a Linksys WRH54G router with the intention of converting this into an access point to distribute our Wi-Fi signal to a room on the floor below us.

I researched on the matter and learned that I have to disable DHCP on the Linksys router (the one that should serve as an access point) and thus use a static IP address for it.

Previously, the internet connection would work without me having to disable DHCP and use a static IP address for the Linksys router. Recently however, this would no longer work on some devices, so I tried disabling the DHCP and using a static IP address, but this would only compound the matter because I would then either be unable to connect to the router or be able to connect but not access the internet.

I'm sorry this is long and maybe complicated, but where did I go wrong in the process? Does the fact that I secured both the router and the access point separately have anything to do with this? Is the static IP address I used wrong (I tried using an IP address one number above the DHCP range)?

Thanks, and God bless!

No. you disable the DHCP server on the AP. You use DHCP to get an address for the AP and you DHCP Forward IP addresses to the clients of the AP