1. Check the Date and Time of the System.
2. Check the internet connectivity and LAN connectivity.
3. Configure your Tally.ERP 9 client license using the Gateway Server
3.1. Start Tally.ERP 9.
3.2. Click C: Configure Existing License in the Startup screen. Alternatively, click F12: Configure > Licensing > Configure Existing License
3.3. Select Gateway Server in the field Configures license using.
3.4. Enter the Server name/IP and Port, where the license is activated. Alternatively, click F2: Gateway Servers to view the compatible Tally Gateway Server(s).
3.5. Press Enter.