For university-related purposes, I have downloaded the Cisco VPN provider. After I disable the connection of the VPN, something strange happens to my wifi connection. My computer can detect wifi networks, and it seems I am connected to wifi at my home, but when I try to open websites, they do not open.
The only solution I came up with is to reboot the computer. In that case, everything goes back to normal. Any ideas on how I can solve this problem?
It’s not a big problem, but it’s kind of annoying.
I think that your VPN connection does not reset your DNS settings once it disconnects, so your system relies on the no longer existing server for DNS queries.
To see if that’s the case, you could check which server nslookup uses for name resolution, e.g. nslookup discussion.fedoraproject.org
which using your system’s (provided by systemd) DNS resolver should give something like this:
If after disconnection nslookup is unable to resolve the name, you can ask it to do so using Google’s (8.8.8.8) or Cloudflare’s (1.1.1.1) DNS server, e.g. nslookup discussion.fedoraproject.org 1.1.1.1. If that is successful, then you’ve found your problem.
If you are using the defaults (again, I think), systemd-resolve --status before connecting to the VPN and after disconnecting, would give you the same information.
You could also see what you have in your /etc/resolv.conf, which nowadays (I think) is supposed to be a symbolic link to /run/systemd/resolve/stub-resolv.conf. Check the contents of the file before and after connecting to the VPN and after disconnecting. Normally, the contents of the file remain the same - essentially using 127.0.0.53 as the nameserver.