If you have a Samsung Galaxy S6 like I do and live in a house with less than complete WiFi coverage you might find you keep dropping off WiFi and into mobile data. If, like me, you don’t have an unlimited data plan this can quickly use up your monthly data and end up costing you money.
I tried various built in settings to keep myself on WiFi but nothing really worked other than turning off mobile data which is annoying to do manually.
So I turned to a tried and true app: Llama Location Profiles (https://play.google.com/store/apps/details?id=com.kebab.Llama).
I have one location: home. When I arrive home mobile data is turned off and WiFi is turned on. I reverse the process when I leave home. Now I don’t have up worry about using all my mobile data in the first week.
Pro tip: when you first start using it, periodically check the location log for times when you are home when it is seeing cell towers that aren’t associated with your home location. Manually add these to the location. You only have to do this a couple of times to get all the nearby towers captured.