I recently got a new Galaxy J7 Crown, Andriod version 8.0.0, Samsung Experience version 9.0.
Will provide more information on software versions as needed.
Phone will continuously lose wifi connection within minutes of being turned on. Wifi signal is still making it to phone, but the wifi symbol gets an exclamation point beside it (!), and gives the message "Internet May Not Be Available" when viewing all available networks.
I believe it is the phone itself, as all other devices work properly on modem/router. Did not do much to the modem/router other than changing the password to ensure my device was the only one on the network. I did, however, attempt to change the wireless channels. Originally it was on auto, but I have tried to use 1, 6, and 11, though we live in a somewhat secluded area with no other wireless networks around, so there should be no congestion on any of the channels. There are at most 3 devices accessing the internet off of the modem/router at any given time. Also, I am at most 15 ft from the modem/router, with no walls or glass or anything between it and my phone.
I have tried forgetting the network on my device, changing the DNS to 126.96.36.199 and 188.8.131.52, full factory reset. Keep Wifi On During Sleep IS set to Always. The only thing that causes the wifi to work again is waiting 10+ minutes, or turning off/turning on wifi.
As for the mobile data, I live in a low signal area and cannot get service until I travel down the road a few minutes. On previous devices, the phone would change signal as needed, but on this device, no logo (LTE, 3G, 1X, anything of the sort) will show up by the bars, and I cannot access the network until I restart the phone. Airplane Mode does NOT work for restoring service. Neither does turning off Mobile Data and turning it back on.
Will give any information needed on request.