One recurring thing that seems to help is to factory reset and not install apps. Just use it without installing a lot of apps. For some this is unacceptable and they flame out over this.
If the issues continue you try on other hotspots and routers. Many routers have out of date firmware so check that too.
My S5 will drop my wifi at home and not pick it back up. I have wasted a lot of data because of this. I stream a lot and now I have to make sure that my data is turned off first just incase the wifi drops. Has anyone else had this problem? It is the on of many problems with my S5 but this is the most annoying.

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