PS4 + Plusnet = Angry Gamer

[#1]

Looking for some advice, our expected speed on our line is up to 78mbps, we currently pay for 32mbps broadband but as speed tests show this is not what we get.
There are two of us in the house, me on my phone maybe watching Netflix and my other half on his ps4...well this never lasts for long, as soon as I start streaming on my phone and his game lags and the game rage starts.

Plusnet done the installation, they ran an extension from the master socket to the games room (upstairs) and we attempted to use the PS4 hard wired to the router but the lag was awful, when we connected it via WiFi things seemed a lot better but if I want to use the Internet I need to insert my earplugs as I know the air will fill with his swear words within seconds. I raised this with plusnet a year ago now but I'm still no further forward. Ive been tempted to buy a new router but is this going to make much difference?
Any gamers or broadband savvi people out there that can offer any advice on stopping this poor broadband experience I'd be glad to hear from you...

[#2]

Can you run the speed test again but using a computer wired to the router when no one is using the broadband service?

Can you also run this BT wholesale speed tester using a hard wired computer to the router.

http://speedtest.btwholesale.com/

At end of the test, scroll down and click on 'Further Diagnostics'.  Enter your  phone number.

Report back with what 'IP profile' is displayed in the Test Results page.

What model router are you using?