No LAN and WLAN anymore, although connection is shown-LM 20:2 UMA Cinnamon-SSD-64B

I downloaded a Proton VPN yesterday. After about 1 hour, the VPN hung. After several restarts, the VPN no longer worked. I uninstalled it and also everything that sounded like VPN Proton in the package management. Something went wrong in the process on my part. The system works but perfectly. But only that the Internet no longer works. Although in the bar "Connected to cable network" is displayed. Also the WLAN USB pen establishes the wireless network, but it does not release a connection. The Fritz Box shows "connected since 03.08.2021, 23:13".

Translated with www.DeepL.com/Translator (free version)