No matter how many hardware or software improvements a company makes to a device, there will always be flaws. In the case of Samsung’s coveted Galaxy S III i9300, Wi-Fi roaming bugs have plagued many user's. Wherever, there is a limitation or a fault, there is always a developer on hand looking to solve it. In this case, the remedy arrives courtesy of XDA-Developers member felixchris.
There are three Wi-Fi roaming bugs in all, and although the fix only deals with one of those problems, it’s certainly a start. Felixchris explains that if the signal strength increases when getting closer to AP2, but then the Wi-Fi icon quickly disappears and reappears right before your eyes (also causing Web radio to briefly cut out), then you’re indeed suffering with the Galaxy S III bug, and his little fix will help you resolve it quickly and effectively.
While applying a patch, there is more than one way to go about sorting out Wi-Fi troubles. The first is the long way, which does not require to boot a custom recovery, whilst the other involves flashing a zip in a custom recovery. Whichever path you choose, both are as effective as one another in ridding your device of the Wi-Fi roaming bug.
An optimal Wi-Fi experience is an important part of owning a mobile device. When at home, we tend only to use our cellular connections as a back-up, since data usage is often limited by our carriers. You should take these steps to fix the roaming issues.