Thanks for the reply, how would I do the highlighted bit? My other phone is an HTC One if this helps. Like I said before, I'm a bit dense on this kind of stuff so feel free to tell me in very basic terms!
HTC One DOES support 5 GHZ band so it should be ok.
This is what you can do. Check your Htc one's wifi networks in the 'settings' section under 'wifi'. If you have a dual band router, what it should show you in the list of networks is your home connection twice, one with a 2.4 ghz suffix, the other with 5ghz. So you'll basically have two networks showing in your list of available connections and both of them will be your home wifi at the two different bands.
What you ca do then is choose the 5ghz band for the Htc One and keep using that band whenever you want to use the internet. You can continue using the 2.4ghz band for your Samsung, it should not slow down any more.
If you are not getting two wifi signals for your home wifi, it means your router does not have the ability to broadcast at 5ghz frequency. Your router needs to be a dual band router. Most half decent routers do usually are dual band so I am guessing you should have one.
If the 5ghz band is not available, the best you can do is not use both of your phone at the same time on your home wifi. Or invest in a new router.
Give it a try...