How to block app and browser ads on the Galaxy S5 without root
Installing Adblock Plus involves a little trickery, since it doesn't require root, as you will have to manually alter the APN for each carrier data network you want it to work on. Here's what to do if you want to block a lot of those annoying advertisements that are flooding our handsets lately:
1. Download Adblock Plus and install on your S5. Make sure you have the option to install from unknown sources turned on in the developer settings menu - turn to our app sidealoading guide for Android, if needed.
2. Start the app, and turn on the filtering option, which means that most ads flying your phone's way will be blocked while you peruse the web on a Wi-Fi network. If for some reason the Wi-Fi network settings don't change automatically, you have to manually change them with the next steps, which are for cellular networks in principle;
3. To turn on ad blocking for when you are on a cellular data network, go to Settings>network connections>more networks>mobile networks>access point names, and long-press on your default carrier connection to enter editing mode. Replace the respective fields with Proxy: localhost and port: 2020, hit the three menu dots at the top, and tap save;
4. On some Galaxy S5 versions the the access point name settings have to be changed manually, and the old APN overwritten, as there's no way to edit it directly. In this case, copy the default APN settings, create a new APN, and fill it in with the copied settings, only replacing the fields Proxy: localhost and port: 2020, then make the new APN your default one;
5. That's it, you should now have a mostly ad-free experience on your stock unrooted Galaxy S5. Not all 3rd party apps can be blocked, and Adblock Plus let's some unobtrusive ads seep through by default, but overall the community is pretty happy with its results, as it's about the only option to enjoy unrooted phones in an ad-free manner.
source: phazey12 (XDA-Devs)