Second router for just games.

I have the Xfinity Gateway router/modem combo and want to use my old Netgear XR500 router for things like my kids older laptop and Xbox 360 consoles that need to have a 2.5Ghz connection in order to connect to the internet. I've read that you have to bridge the Gateway which you'll loose the router capabilities of it and I'd like to keep those for the higher connections to our phones and such. I've had two issues I'm looking to solve which is why I'm doing it.

1. The Dell laptop is from 2016 and still works great after the new SSD and upgraded ram I put into it and I upgraded the OS from windows 7 to windows 10. With an ethernet cable it connects just fine to the internet but when I try to use Wi-Fi it shows everybody's else's Wi-Fi but mine, though there is a couple hidden but I can't connect to it. It's not hidden and all my other devices find it with no problem. It was suggested that the laptop (Inspiron 7737) uses a Wireless-N card so the higher wi-fi signals may be what's preventing it from connecting or seeing the network. It did work fine before when I just had the XR500 as my router.

2. I have 5 Xbox 360's and can not get any of them to work with either an ethernet cable or wi-fi through the Xfinity gateway. Some will connect but wont really do anything. From what I've read people have had to use a second router and "dummy" it down in order for the Xbox 360 to connect and work properly as once again the old tech in the gaming system. I've seen some doing it by opening ports while others mentioned about turning off the 5Ghz and only using the 2.5Ghz wi-fi connection.