The “Connection to server lost” message means that problems have occurred with the exchange of data between your computer and the game server. In most cases, this message is caused by a network hardware malfunction or misconfiguration.

Please try the following steps:

1. Reset your network equipment. This helps prevent any devices from being overloaded. If resetting your equipment does not help, try turning your router off for a few minutes and turning it back on.
2. If you are using a wireless (Wi-Fi) connection, try connecting directly via LAN (Ethernet cable).
3. Close any other applications that use the Internet, such as torrent clients.

Please note that 3G and 4G modems may seem to supply sufficient speed but are in fact not stable enough to provide a reliable Internet connection. The game client performance and stability are not guaranteed if you are using a 3G or 4G modem.
Also, if your Internet Service Provider uses NAT (Network Address Translation) or you are using a proxy server, we, unfortunately, cannot guarantee that the game client will operate correctly.
 
You may find a few suggested router settings to be helpful.
Try these recommendations:

1. Enable DMZ.
   • In your router settings, find the DMZ Host menu or tab. Most models have this setting under Advanced ⇒ Firewall&DMZ.
   • Click “Enable” or check the “Enable DMZ” checkbox and enter your computer’s IP address.
2. Disable SPI.
   • In your router settings, find the SPI Mode or SPI menu or tab. This is usually located in Tools ⇒ Misc.
   • In the SPI Mode tab, uncheck or deactivate (“Disable”) SPI.
3. Update your router’s firmware to the latest version.
   • To upgrade your router’s firmware, please visit the router manufacturer’s official website. You can also ask your Internet Service Provider for the necessary setting.

If your connection’s setup allows you to connect without a router, try doing so.