Galaxy Tab A wifi will not stay connected on some networks?

My tab A works fine on my home network. At work or school (public networks) my tab A will disconnect and reconnect to the wifi. My phone and laptop both work fine everywhere so I know it is a issue with my tab A. Any ideas? I tried correcting the date and time. Tried clearing data cache. Tried update. Tried disabling bluetooth. Tried setting connection to "always on" during sleep. Still nothing. It will stay connect for 10 seconds or sometimes 5 but keeps dropping and reconnecting. Anyone have an idea. I cannot adjust the router settings because they are public places.