get any access point/extender will do. but depends on your modem location (house/room).

alot diff..access point is to boost the wifi coverage. router is only for dial up only. some router do have built in access point but its crap for me.  would prefer to get access point ( pure) and range extender is similar with access point but diffirent on the configuration. you better change the new modem and router better. another is either you get powerline will do.

for which one you looking?unifi?

yup same thing i used for my unifi recently already got aweek liao using unifi.   just that you need the proper configuration for maxis settng will do. if you stay in single setorey then that router should be able to handle the coverage else you need access point/ extender or powerline with at least av500 > this can boost the performance.