LAN Connectivity Isues and Poor WiFi signal on XR500

I have recently bought the Nighthawk Pro Gaming router, the XR500, in order to stabilise my internet connection when gaming and in preparation for when I get Sky Fibre installed next Sunday, an upgrade from Sky Broadband Max. However on setting up the XR500 with my current SkyBroadband Max, though I can get decent internet through a wired connection, the Wi-if to all my devices around the home is much weaker, and keeps dropping off. Can anybody help solve this issue? On setup, I connected the cable between the sky router and the Netgear XR500, and disabled the wireless access point on my SkyBroadband settings page. Do I have to do anything else? I have tried disabling smart connect and using the two options, but this has failed to improve matters. Now I am also unable to connect to the internet using the LAN ports, and my internet browser justs say the website refused to connect, even though it says its connected. I’m not sure what’s gone wrong, as it was working before. Can anybody help me? I am very new and inexperienced to this, so try and explain any help or suggestions in a very basic manner, and help guide me through each step. Any help much appreciated.