I am a consultant and frequently use my Galaxy S5 as a mobile hotspot for my laptop at customer sites, which works perfectly. However, when I disable the hotspot when I get home, frequently (although not always) the phone will connect to an access point but I can't access the Internet. If I turn off wifi I can get Internet fine over the 4G network. If I restart the phone it connects to wifi and I can get to the Internet without a problem. I have experienced while attaching to different access points and SSIDs.
While the phone does restart quickly, this is a step I would prefer to avoid. Any idea what the problem is?