Netgear nighthawk r7000 and ARRIS SURFBOARD SBG6900-AC

Hello everybody i hope somebody can help me im not a techie guy so if you can do step by step on the solution that will be very helpful so i have a netgear r7000 and a arris sbg6900-ac i live in a townhouse kinda in the middle there are 4 houses including us. i bought a netgear r7000 to make our internet signal better because 4 houses close together make the connection slow and we are like sharing the signal of the internet. So long story short first few months that i had the netgear everything was working fine didnt have any problems after couple months ive been losing wifi connection so everytime that happen i restart the arris and netgear then it will work time pass by i keep losing wifi connection the whole day i keep resetting the modem and router like 5 times a day and it works normal again i call my provider ask if there was outage they said no everything is ok like signal and other stuff. So what should i do? I have the netgear for almost 1 year and the arris for 2 years...should i buy a new one?by the way i turned off the wifi on the arris and put the netgear to ap mode