If internet connection is hacked, computers will become vulnerable. Although maintaining security on the user's machine will probably mean that security overall will be sufficiently maintained, it is still worthwhile safeguarding against such an event.
It's best not to use a shared WiFi router at all, if it can be helped; or if it is used, only to use it with a highly secure client-machine set-up. When a router is shared, it can be difficult to convince others about the need to perform certain security tasks, such as the changing of the WiFipassword on a regular basis. Essex police’s cyber-security advice as of March 2020, was not to use free WiFi for anything you wouldn’t want a stranger to see.