My laptop says it's connected to the internet but it isn't?

I just got a new Lenovo G505s laptop with Windows 8.1 a couple of weeks ago. I connected it to my Wi-Fi and everything worked perfectly fine. For the last few days though I've hardly been able to access the internet with it.
It says "BTHub4 - Connected" but anything that requires an internet connection isn't working, including web browsers.
It's been working sporadically; it worked for about an hour yesterday morning and about half an hour this afternoon, but other than that nothing for 3 or 4 days.
I've tried right clicking on the Wi-Fi symbol in the bottom right hand corner and clicking the "troubleshooting and solutions" option, but it just says "Windows couldn't identify the problem"
Sometimes the list of available networks is replaced with "No available networks" but mostly it says I'm connected when I'm not.
I'm not having any problems with the internet on my old laptop or my phone, so I'm pretty sure it's just the laptop that's the problem and not the internet.
Any suggestions on what to do?