i have config below

router (192.168.100.1) --- CPE710 (192
168.1.254) --- CPE710 (192.168.1.253) --- broadcast wifi 5ghz

wifi is working now. connected ip 192.168.100.xxx

i want to connect ip cctv (require 2.4ghz or wired connection)

what cheapest option i have here?

Tp link omada 2.4ghz access point last time rm 99 only now don't know, outdoor access point, or existing 10 year old wifi router disabled DHCP turn into access point ,

Last location matter if your car park have 2 wifi CCTV installed u need install one of the access point at carpark too if you install access point at living room with TV location got glass door, wood door, concrete wall, steel fence the signal is sucks

Last Don't use wifi range extender they all sucks

is it possibel to have 1 router connect to 5ghz wifi as WAN and cctv connect to router via LAN cable? what router can use for this?

Possible

This is known as wireless bridge mode

These days I think only ASUS still support it, they call it media bridge mode