iPhone 7 Plus Wifi Connectivity Issue

My iPhone 7 Plus got wifi connectivity issue when updated to iOS 12.1.4. It disconnects after 1 minute of using it from sleep then I have to restart the phone to connect again. I have restarted the phone and reset network settings but the problem persists. Why iOS devices are having problems with wifi/data connectivity nowadays. These feature really makes our phone useable and now they are like trash for failing to work on that basic feature.