1- In Winbox, go to System > Resources and look for Architecture Name in the bottom section:
2- Go to MikroTik Routers and Wireless - Software , find your architecture and download the main package, either Long-term or Stable version:
3- Back to Winbox, go to Files
- Drag and drop the downloaded .npk file to the File List.
- Reboot the router (System > Reboot) and wait for the upgrade process to finish.
Do not turn off the router during this time!