In case you are experiencing issues with your Mysterium VPN connection on macOS, resetting your network settings is a viable option to resolve them.
The most effective method is to delete key network configuration files (macOS will automatically recreate fresh ones on restart). Follow the steps below:
Open Finder and select Go > Go to Folder from the menu bar (or press Command + Shift + G).
Type or paste the following path and press Enter:
/Library/Preferences/SystemConfiguration/
In the folder that opens, select and move the following files to a backup location (e.g., your Desktop) in case you need to restore them later:
com.apple.airport.preferences.plist
com.apple.network.identification.plist
NetworkInterfaces.plist
preferences.plist
com.apple.smb.server.plist (if present)
Restart your Mac.
After restarting, reconnect to your Wi-Fi network (you may need to re-enter passwords), then try connecting to Mysterium VPN again.
Additionally, to flush the DNS cache (which can help with connection issues), open Terminal (found in Applications > Utilities or via Spotlight) and run:
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
Lastly, enter your administrator password when prompted and press Enter.