Setup for best speed for gaming

[#1]

I have just got Plusnet 900 full fibre.
My question is the ONT box is downstairs at one side of the house and my sons room where he uses gaming pc is on second floor at the other side of the house.
He is using a netgear powerline 1200mbps to connect his pc atm but he’s not achieving max speeds.
I have a netgear xr500 router. Would that be better than the Plusnet?
I know a wired connection for gaming is always best but it’s too messy to wire inside and up the stairs through hallways etc.
A relative that works in IT said a could get a cable from the ONT run it outside to the upstairs room. But would that then mean router would be upstairs and all downstairs appliances would need plug in power lines if the Wi-Fi isnt reaching?
Any ideas on how to set up so get max speeds for my son would be much appreciated.

[#2]

Assuming that the router is next to the ONT, the externally run of CAT5 (network cable) would use one of the ports on the router.

[#3]

He is using a netgear powerline 1200mbps to connect his pc atm but he’s not achieving max speeds.

@Jilc77 In my experience the quoted speed of powerlines is completely fictional. I have a pair of 1000av ones and they max out at around 150Mb and that's if they are on the same electrical circuit. On different circuits they can be as slow as 25Mb!

as @mystreet1 says, to get the full speed of a 900Mb connection, the best way is a wired connection.

[#4]

@Jilc77 

Ethernet cable is always recommended if possible, and especially for gaming.

An external cable would cost a bit of money but gives guarenteed speeds and is future proof. As stated, you would simply plug one end into the router and the other into the gaming machine. Or it could be plugged into an ethernet switch with the gaming machine and a WiFi Access Point (WAP) connected.

I've always suggested ethernet wall sockets with short cables at either end but another poster has stated they are not particularily easy to retro fit without taking plaster board off the wall.

Brian