this may help. I experienced this problem once but not for my S7e. it was on my tablet with wifi 2.4/5GHz capable.
I changed 5ghz channel in my access point to match the device's country allowance channel. and it's work.
see...
I am in Thailand. This problem happened to my 4months old S7e too.
Samsung agreed to give me a new phone. but after 14days during my 3weeks waiting for a new phone, this problem just disappear!!!
Anyway I will change a new phone with Samsung.