Problems with unwanted redirecting ads on safari

Hello Everybody,

I bought one month ago an iphone 6s on IOS 9.1. I encounter a problem when I use safari and want to go on websites. Sometimes, when I go on a website, this one doesn't open and I'm redirected to an advertising page..always the same one! Plus it happens whenever I use a wifi or a 3G/4G connection. I have rebooted my phone once but it happens though. So I wonder if this is a problem due to my connection or to the phone and what can I do to resolve it?

Thanks for your concern.