I have been using Ubuntu 16.04 for a couple of months now. There is this weird issue I have with the wifi. It connects after booting and works fine for a variable amount of time, after which it still shows that it is connected but there is no internet access. I tried disconnecting and reconnecting but then it stops showing the availability of the network altogether. Please give me a sep-by-step solution to fix this. I am a new Ubuntu user and not very familiar with commands.