Android 4.2.1 Wifi Never shut off option does not exist
I just purchased a new 7" generic non brand tablet (it is sold by lightahead but no idea who actually builds it). It was cheap, but runs better then my years old beast dell streak ever did. The only thing I cant figure out is how to force the wifi to stay on while the screen sleeps. I know it SHOULD be under settings - wifi - advanced. But the option is just not there. One of the main uses I use the tablet for is the yahoo messenger program, and if it shuts off wifi while sleeping, then I cant exactly get messages anymore.
I tried several supposed apps that would force it to stay on, but they did nothing. One was supposed to toggle the switch between stay on and turn off while sleeping, but it did not toggle, it would just say it is now set to default, and to turn wifi off during sleep. The only option is to never sleep, but that is a battery draining way to do it.
Any help would be appreciated, and also where do I find information about these generic tablets? Someone somewhere must build them. I have seen the exact same tablet with a dozen different names from a bunch of different places.