Router FW: 6.46.1
No packages installed manually before, plenty of space.
Put multicast-6.46.1-mipsbe.npk over FTP and can see it in the file list. (HAP AC is mipsbe as far as I see on resources tab)

Rebooted the router, but nothing happens. The npk file is there and there is no message about it in the log.

Any clues?

Is there anything in log about it? If there's nothing, then npk file location is probably not right.

Is there anything in log about it? If there's nothing, then npk file location is probably not right.

Nothing in logs.
When joining via FTP I see that root folder's path is "/flash". (with no way to get to the / folder)

Uploaded file via UI to the actual root folder, and it worked, thanks.