WireGuard VPN Troubleshooting Guide

If you're unable to connect, check these common issues:

1. Check if WireGuard service is running:
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   sudo systemctl status wg-quick@wg0
   
2. Verify the server is listening on the correct port:
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   sudo netstat -ulnp | grep 51820
   
3. Check firewall rules:
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   sudo ufw status
   
4. Verify IP forwarding is enabled:
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   cat /proc/sys/net/ipv4/ip_forward
   
   Should return 1

Connection drops are often caused by NAT timeout or firewall issues:

1. Add PersistentKeepalive to client config:
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   PersistentKeepalive = 25
   
2. Check server logs for errors:
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   sudo journalctl -u wg-quick@wg0 -f
   
3. Verify MTU settings match on both server and client (recommended: 1420)
4. Check if your router/firewall is blocking UDP port 51820

This error occurs when the interface is already active. Fix it with:

Or restart the service:

Several factors can affect VPN speed:

• Server location: Choose a server closer to your physical location
• Server resources: Ensure your VPS has adequate CPU and bandwidth
• Network optimization: Follow our VPN Tunes Up guide for performance optimizations
• MTU size: Set MTU to 1420 to avoid packet fragmentation
• BBR congestion control: Enable BBR for better throughput

To add additional peers:

1. Generate keys for the new peer (on client device):
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   wg genkey | tee privatekey | wg pubkey > publickey
   
2. Add peer to server configuration:
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   sudo wg set wg0 peer <PEER_PUBLIC_KEY> allowed-ips 10.8.0.X/32
   
3. Save configuration:
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   sudo wg-quick save wg0
   

This usually indicates a routing or NAT issue:

1. Verify IP forwarding is enabled:
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   cat /proc/sys/net/ipv4/ip_forward
   
2. Check iptables NAT rules:
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   sudo iptables -t nat -L -n -v
   
3. Verify PostUp rules in server config include MASQUERADE
4. Check if client config has correct AllowedIPs (use 0.0.0.0/0 for all traffic)

Use these commands to verify your VPN:

1. Check WireGuard status:
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   sudo wg show
   
2. Test connection from client:
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   ping 10.8.0.1
   
3. Check your public IP (should show server IP when connected):
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   curl ifconfig.me
   
4. Test DNS resolution:
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   nslookup google.com
   

To change the listening port:

1. Edit server configuration:
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   sudo nano /etc/wireguard/wg0.conf
   
2. Change ListenPort to your desired port (e.g., 51821)
3. Update firewall rules:
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   sudo ufw allow 51821/udp
   
4. Restart WireGuard:
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   sudo systemctl restart wg-quick@wg0
   
5. Update client config with new port in Endpoint

To remove a peer from your VPN:

Or edit the config file directly and remove the peer section, then restart the service.