iPhone 6 wifi problems

hi my iPhone 6 constantly crashes and/or drops signal on my home wifi and has done since I got it. This issue is only with my phone - my husband has an iPhone 5, I have an iPad Air and my stepdaughter has an iPhone 4 all of which work fine on our home wifi, as does our Toshiba laptop. My i does not have this issue with any other wifi network.

when I am at home the wifi signal sign on the top of the screen goes on and off between wifi and 3G every couple of minuteS. Websites are almost impossible to use and my whole phone slows up and freezes. It's making my phone almost impossible to use in the house. Often my phone says there is no internet connection although the wifi symbol is showing. Some days and times are worse than others but it's always like this but as I say only at home. i have had the phone about a year sand have updated operating systems etc.

I live in the uk, wifi router is suplied by Sky and I'm on O2 network. Please help me it's driving me crazy!