Interestingly, I only just got my G751 last Saturday and initially had problems getting it connected to WiFi as it was doing exactly the same as yours, but it eventually started connecting properly and everything seemed to work fine.
And then it started freezing.
To cut a long story short, I ended up reinstalling Windows 8.1 from scratch along with all of the drivers and now it is running 100% better than it was when I first got it. It also means that I know exactly what's on my machine as there's no bloatware or hidden apps that I don't want. I wouldn't go as far as saying that you should give this a go too, but it may be worth considering if you're having problems.
Asus ROG G751JT-T7115H
17.3" IPS, Intel i7-4720HQ, 16Gb RAM, NVidia GeForce GTX970m, 256Gb M.2 SSD + 1Tb SSHD