I read numerous threads on this, not only here but elsewhere. I talked to Samsung tech support and they were not that helpful. During thwe conversation, I went into the router settings under Wireless and then Access control.
I add the MAC addr of my S5 and indicated "allow". It has not dropped the wifi here at home. Since I did this, I went to store, came back and it connected the way it should, silently. Believe I am done with this challenge.
It may work for those having the same challenge. Best wishes.@