Slow or non existent WIFI connection with Dell Inspiron 13-5000 model Z510840AU

I've just bought this new laptop and it won't secure a stable connection with my WIFI at home. From a few other forums it looks like this is a common problem but I'm not sure how to fix it? All other devices in my house are all unaffected, everything else is connected fine - just not my laptop. I've turned everything off an on but still no change. Any ideas?!? I'm losing my mind!