Wireless internet/router help

My brother and I play ps4 online together and lately we've been playing and when I host a job on gta or other games I alwayslose connection. I've got a Cisco EA4500 and I've got 30mbps coming in through our cable company and our modem is rated for this speed. My modem and router is only 3ft away from the ps4. the other night I played with him with no problems but I was using a wired connection directly to the modem but the rest of the house my wife couldn't use our wifi on her iPhone or tablet. I Did go into the setting on the router and put the ps4 and our two iPhones priority on top. Haven't played wirelessly since I've done this. Not sure if that will help. Also I was thinking about te ports on the back of the router where you can plug an Ethernet cord up to and then plug into the ps4. Would this work or be an option? Anybody know a solution for me so I won't lose connection while playing games online