Start with the local network
Before changing VPN settings, confirm that Windows has working internet access without the VPN connected. Open a normal website, then test a second site to avoid being misled by a cached browser tab.
If you are on hotel, airport, guest, or coffee shop Wi-Fi, complete the captive portal first. Many public networks block normal traffic until the browser login page is accepted.
Check account and entitlement state
A VPN connection can fail because the account is expired, trial access ended, or payment status changed. That is not a tunnel problem; it is an access state problem.
If the client has an account or status page, check it before troubleshooting adapters, DNS, or firewall settings.
Check Windows basics
Restart the VPN application. Disconnect and reconnect Wi-Fi or Ethernet. Confirm the system clock is correct. Check whether a local firewall or security product is blocking the VPN client. Reboot Windows if the network stack appears stuck.
When to reinstall
Reinstall only after you have confirmed the network works, account status is valid, and no local security software is blocking the client. If reinstalling, download the latest installer only from the official ZBEVPN download portal.