I have a new router and using my old TP Link Router model W8691N as a repeater. The wi-fi icon on the router stays on but the message i get on my computer is that the router is connected but there is

Hi I would like to disable the DHCP server on my router . How do i do that? Secondly, it seems as if my router is not compatible with Tether. How do I solve that? Am in South Africa. Thanks Mokgoro