How many different WiFi points have you connected the tablet to? Does the tablet behave the same way, regardless of the wireless router?
Pretty much every time I have experienced something like this, it has been down to the router, not the tablet / phone.
Most of the time, you can adjust your router settings and it can solve the problem. Go in to your router settings and see whats going on. Is your router broadcasting on both 2.4 and 5Ghz? Has the router any "smart channel switching" technology going on? What is your wifi security policy?
Try changing these options and see how you get on