If you are using in your household a wireless repeater, so as to supply the entire house with a strong Wi-Fi network, you might have the following problems with your Samsung Galaxy S5:
The Samsung Galaxy S5 remains so long in one access point until the connection is too weak, although a stronger access point is nearby. Despite the stronger Wi-Fi signal near your phone so stay in the old access point to log in or associated with it. Thus, of course, your Internet speed on the Samsung Galaxy S5 is not as fast as it could be.
If this bothers you, then you should test the following useful app:
The app is "Best WIFI" and regulates precisely these problems. The app checks to see if a stronger Wi-Fi signal is available and thus connects automatically, if you have previously set. The app "Best WIFI" can be downloaded for free from the Google Play store and is definitely worth a test if you are struggling with the above problems.
You should be with your Samsung Galaxy S5 and a Wi-Fi network anywhere have the best bonding strength with WiFi repeaters.