Authentication error on laptop and mobile phone since I connected to my friend's Wi-Fi?

Now I have no Wi-Fi anymore. But ONLY on these 2 devices. Have already reset to my phone on factory settings, brings nothing… What now?

I'm confident that we will get it solved quickly.

An authentication error classically indicates a wrong password. Please check once in the router, which security key is deposited and then enter this new in your phone.

If that does not help, please change the security key in the router and accordingly, of course, in the devices that should connect to the router.