@MuraliBijjur 

If you disable Secure Sharing, are you able to access the ftp://192.168.1.1 (since port 21 is the default FTP port, it can be omitted) ?

If yes then that's the problem. See these notes from your device user guide:

Note:

1.For Windows users, do not set the sharing username the same as the Windows username. Otherwise, Windows credential mechanism may cause the following problems:

•If the sharing password is also the same as the Windows password, authentication will not work since the Windows will automatically use its account information for USB access.

•If the sharing password is different from the Windows password, the Windows will be unable to remember your credentials and you will always be required to enter the sharing password for USB access.

2.Due to Windows credential mechanism, you might be unable to access the USB disk after changing Authentication settings. Please log out from the Windows and try to access again. Or you can change the address of the USB disk by referring to To Customize the Address of the USB Storage Device.

@MuraliBijjur 

These logs are concerning:

2021-08-20 15:50:38 Led Controller ERROR [1091] Config importing failed

2021-08-20 15:50:38 Led Controller DEBUG [1091] Failed to read USB3

It's quite possible that the FTP service is not started, hence rejecting connection on port 21.

Look at the Kevin's suggestions from this thread.

Thanks @terziyski for the quick and valued suggestions.

@MuraliBijjur Can we know the format of the HDD? If possible, try to reformat it to FAT32 or NTFS, then check again.

BTW, please send us the whole system log on the AX20 via email, we will confirm.