update:
Sometimes the internet connects well, sometimes the connection is very slow and most of the times I can’t connect at all. When I try to ping 10.0.0.138, the packets are either lost or it says: “Destination host unreachable”.
After a long time, I received a good connection, so I ran yay to update the packages. After that, the problem didn’t appear again. Before I got this good connection, I tried to connect a different WiFi.
My WiFi device is Realtek RTL8188EUS.