rt n12+

I have Excitel optic fiber connection at my home. Using Optilink router OP-XOT 71110AC (https://optilinknetwork.com/SUBSCRIBER-END-EQUIPMENT-OP-XONT-71110AC) as my main router and wanted to extend its wifi range using an Asus RT N12+. I have tried configuring RT N12+ in repeatrer mode atleast...