I can suggest to reset the router to factory default settings and try again.
Double check device's connectivity to the internet.
Check, if your desired package cannot be found in this page and uploaded to the router.
Alternatively, login to the device via SSH, execute command below:
Then append the following command with the name of the package you want to install:
- opkg install <package name>
You can list available packages with:
In case you are looking for something specific, you can add | grep to the following command.