I have had problems with the wifi settings on my phone since I got it about a year ago. I have the S7 edge which I had to trade in my Note 7 for. I posted about this problem when I got this phone and as of today never got an answer that really solved this problem. Supposedly in one of the update patches they said there was a fix in there that would take care of the problem I see this morning that people with the S8 got an update and are having this problem. I too have rebooted the router and it seem to work at first but disconnects after awhile. One of the things I have done that seems to last longer is going into settings-backup and reset- and go down and reset network settings. Like I said it is not the fix for this problem but it does seem like it lasts longer then rebooting the router. Until they get a real fix for this I would recommend that you turn off mobile data if you are at home or at some place that has a wifi router that you can connect to. Hopefully they will hear us and get this fixed.