Galaxy S8 using too much internet

Take it back as you've encountered problems with it. Not fit for purpose. Go back to your old phone. Not worth the hassle or a new contract when something like this happens.

PS you are within you rights as there is a 'cooling off' period with a contract. This may help .

I think I can resolve the problem as I like the phone apart from that issue

Moved to Digital Home and Smartphones Help from Tech Helproom.

That is strange that the router would give the phone priority on the wifi.

What is the speed of your internet connection?

Only thing I can thing of is setting the QoS on your router (Quality of Service) so that the PC always has a good connection.

I've had to do this in the past when sharing a home connection with heavy downloaders which affected my streaming.

Its because of heavy specs of Samsung Galaxy S8.

I have about 12mbps download, how would I change my QoS?

It varies slightly by router, what sort of router do you have?

Just a thought.

When you buy a new phone, it will have been sitting in its box on the shelf for quite a while and its software will need any number of Updates.

If this is still happening in a weeks time, you may have a problem, but I would have thought that your initial experience was fairly normal, possibly exacerbated by a less that sparkling Connection Speed.

I think I may have fixed it by reseting app permissions, did it 2 hours ago and has been fine since.