Range Extender for Sagemcom 5260 Wireless Router

Hello... Last week I upgrade my home network. From my home ISP provider, Optimum Online, I upgraded my Internet Service plan to the Optimum 100 speed. They replaced my modem and Wireless Router. They provided me with the Sagemcom f@st 5260 router. Unfortunately the tech support from my ISP provider were not able to provide me with the necessary specs so that I could shop for a range extender that would best work with this router and the upgraded 100 speed. Unfortunately I could not find much info regrding this router to help me with my purchase. I would like to seek assistance in making a purchase of a new Netgear AC Range Extender. Would anyone know which AC range extender would work best for this Sagemcom 5260 router? Please advise...