On my iPhone 7 Plus, everything will be fine and suddenly it won’t have a connection. Worse i can’t even go into Wifi settings. Settings will just hang if I do that. I also can’t toggle Wifi off in control panel. My only option is to turn the phone off and on.
I just updated from iOS 12.4.1 to 13.1 and it’s happened three times in the last hour. I have a ASUS router.