Ethernet connected but no internet connection in Ubuntu 20.04 [duplicate]

I tried to install ProtonVPN on my Ubtuntu 20.10 via official ProtonVPN documentation. After installation, I noticed ethernet icon appearing on top-right but internet was not working. I then uninstalled protonVPN but still internet is not working even WIFI is connected. There's still ethernet icon top-right. I tried using my phone's internet via USB tethering, I was able to connect tethring but internet was still not wotking.

How can I solve this?

This question is pretty old but I had the exact same problem with the exact same distro so I'll answer with how I solved it after uninstalling protonvpn. By running

nmcli device

I found out I had two extra connections that had remained there and the system was trying to route through them, so after identifying them I simply did

sudo nmcli connection delete pvpn-killswitch
sudo nmcli connection delete pvpn-ipv6leak-protection

After that rebooting solved everything.

The official Protonvpn installation page is giving the same solution with a few extras: Remove any leftover files:

rm -rf ~/.cache/protonvpn

And

rm -rf ~/.config/protonvpn