If your router is connected to the internet, you can access the device via CLI/SSH and enter the following commands:
- opkg update
- opkg install <your_desired_package>
You can also download packages to your PC and transfer them to the router using WinSCP software. Once the package is uploaded, use command
- opkg install </your/directory/Package.ipk>
Could you also tell which firmware version is your device using?