I bought Dell Inspiron 14 (5447, Early 2014). Wifi is extremely slow, when my old laptop and other laptops in the location having good speed. So i gave my laptop to service center but still having same problem. They said they have changed wifi adapter.
I tried updating driver, checked wiki adapter band status etc. I think this is not a problem with the router.
Please let me know if anything can be done !!
Below are some links to maybe help increase your wifi signal.
I have exactly the same problem on my dell inspiron 14(5447) and I bought it on Auguest,2014, I just want to know do you solve your problem already?