E 6420 randomly shuts off

​Hi, I have Dell E 6420 Latitude Intel Core i5 pro Windows 10. It has 2 ongoing issues :​

​1) Upon during normal surfing laptop randomly shuts off without any error message and I have to reboot it again, which takes a while, but I have set all settings in screen off to "never " despite that randomly its shutting off. It seems to be an issue with lot of dell laptops as I read across the forum.​

​2)the wifi also gets disconnected randomly and would not reconnect even though the wifi is on full range and wifi range is showing full on the wifi section, but it just be reconnect.​

​Kindly advise. ​