I am having the same issue and it is not the router. The tablet was connected one night and the next morning there isn't even an option to connect. The troubleshooter said there was a Realtek issue. 4 other devices are connected just fine but the tablet doesn't seen to even recognize the ability to use wifi. This happened after doing a Windows 10 update which required me to remove most of my stuff anyway to create space for it. I tried to do a factory reset and guess what? I have to free up more memory to factory reset! I have no additional apps and I removed all my personal files so there's nothing else to remove. I don't know what to do now. Good luck!