My Mac and iPhone both can't connect to wifi

My best guess is something is corrupted in your iPhone's networking settings, and it may have been transferred to your Mac when you connected the cable. One question, do other devices still connect OK to your WiFi? Could it be a router problem? Any teenagers in the home who might know enough to be dangerous while trying to evade restrictions on access to internet?

Suggestion: For testing, Rename your router SSID. This will make it a new connection and you will have to setup again so you should have a clean configuration if it works.

Now fixing the problem if a new SSID doesn't help or you want to go back to the old SSID... I suggest you power down the Mac (at least disable the WiFi) to avoid any interference while you try to fix the iPhone. Sorry I only have the English setup to give me the menu options, with luck you should be able to find them in the French version.

In the iPhone go to Settings / General / Reset and tap Reset Network Settings. Try to get back and connect to the WiFi, expect you will need to provide your router password again.

If that does not help the universal fix would be to Erase the iPhone and setup again. You probably wish to have a recent backup for this, which might be a problem if your home WiFi doesn't work (try a different WiFi like a cafe or bar). When you are content you have an adequate backup or at least the best available, go to

Settings / General / Reset and tap Reset All Settings Hopefully this will remove any corrupted settings without having to setup like a new phone. If not, go to the same menu and select

Erase All Content and Settings

Then begin the setup process like a new phone. You will also need your AppleID and password to get into Activation Lock.

have you attempted to pull the power plug if your wifi router for 30secs ?

iPhone 5S

Please open Settings and then Wi-Fi. Then open information page ( click the i in the circle next to your wi-fi connection ). What do you see there ? Any screenshot you can give here.