Sims 4 Launch and Playtime causes Internet Connection on PC to die completely.

CatBuzzz​  Please delete some temp files on your computer:

• Click Windows key-R, and a run box will appear in the lower-left corner of the screen.
• In the new window, type or copy & paste "%temp%" (without the quotes), and enter.
• Now your Windows Explorer should have brought you to the C:\Users\[your user name]\AppData\Local\Temp folder.  Delete all files and folders inside.
• If some files or folders can't be deleted, restart your computer (a real restart, not sleep/wake) and try again.

Additionally, before trying again to open the EA App, clean-uninstall it with Revo Uninstaller (the free version is fine).  Use the Intensive scanning method when asked.  Restart your computer and download a fresh copy of the App installer from here:

https://www.ea.com/ea-app#downloads

Run it as an admin: right-click the download and select "Run as adminnistrator."  Then open Sims 4, while fully online, and see what happens.