Severe Fibre Broadband Speed Drop-off

[#1]

My fibre broadband was installed on 27/08/14.I am using a BT Home Hub 5.
The only access point available for the router is in an outhouse 2 meters from a sidewall of the kitchen (the previous occupant ran a business from the outhouse).
I can get speeds of 60 download and 20 upload with the PC directly connected to the router by ethernet.
The wireless wifi coverage in our 3 storey semi is abysmal. This is with using Powerline adaptors.
The kitchen is not too bad with Powerline with a download speed of 20. I can live with that facing the alternative of running ethernet cabling from the outhouse to our 1st floor. My wife has banned me from any cabling.
It is in our lounge where my sons have a recently bought X Box One where the signal deterioration is shocking. Consistent Broadband speed tests give download readings in the range of 7-3
. Upload speeds are relatively good at 5-11.
My sons are in uproar as they cannot do live gaming with the current broadband speed. Yet the Sky 8 speed service was adequate
My wife is insisting I change back to the standard Sky broadband as her tablet is not usable.
The rest of my family use smart phones connected to the internet ( I don't) which are also unusable.
How comes the standard Sky broadband speed was so consistent and the fibre broadband is so variable between ethernet and wifi?
Any ideas anyone as I have done two days research and wifi extenders look dodgy at best and I am prohibited from using any ethernet cabling?

[#2]

Where you using the home hub 5 when you were on sky? If not, I'd suggest that's your problem. The variable speeds over wifi are nothing to do with it being fibre broadband, it's purely down to the wifi signal coming from the home hub 5.
Wifi by nature is variable and is very susceptible to interference, for gaming, you really need to be wired. I'd suggest either taking a look at power line adapters, or take a look at a new router with faster wireless coverage than the Home Hub 5 (this means it'll be  quicker with less signal). You have to make sure the devices are capable of using these speeds though.
As a shorter option, download a free tool to scan the wifi networks around you and find out what channel they're on, and set yourself to the channel with the lowest signal interference from other users in the Home Hub 5 settings.

[#3]

Thanks for this response. I have only switched to the BT Home Hub 5 since I switched to Plusnet. I am using Powerline Adapters - Powrerline 500.
What is the free scanning tool that I can use to check for the wavelength of any interfering routers? can you suggest some faster routers that I can use instead of the BT Home hub 5. I am thinking of using the plusnet Hub which has received a rave review on Which? Online but I understand is not rated by the Plusnet community?
Regards

[#4]

I don't rate the Plusnet router. Personally I use the TP-Link WDR3600 as that is capable of 300Mbps wireless n (I believe the Plusnet router and BT Home Hub are only up to 150Mbps wireless n) However, you have to make sure your devices can handle these speeds.
I don't know of any specific apps for Windows as I'm a mac user, however Google throws an application called inSSIDer which seems to be reviewed by a fair few websites. There's also another one called Wireless Wizard.

[#5]

Quote

What is the free scanning tool that I can use to check for the wavelength of any interfering routers?

If you have an Android tablet (or phone) then this https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer&hl=en_GB is simple to use.

[#6]

Neither the 582n nor the HomeHub5 are "150Mbps" 1x1 11n devices. They are both "300Mbps" class devices (2x2). The HomeHub5 is also can use the 5GHz band, perhaps check the Xbox One is connecting to the HomeHub5 on the 2.4GHz band, which should have longer range than the 5GHz band. You probably have to give the 5GHz network a different network name (SSID).
Acrylic Wifi looks more capable than inSSIDer was, and it's also free, unlike inSSIDer v4.
Just because you can see other networks, and even if they are on the same channel as your network, it doesn't necessarily prove that those other networks are the cause of your problem. There was this thread but unsurprisingly that thread resulted in nothing much.