It looks like the string "ap3g2k9w7tar1533jpn1tar link" is not a standard academic paper title, DOI, or known identifier.
: In software or gaming contexts, such strings are often used as product keys, game keys, or activation codes. They are crucial for software licensing and verification. ap3g2k9w7tar1533jpn1tar link
If you see this in your logs, check if tar1533jpn1tar is supposed to be a file on your TFTP/FTP server. Run file command on it in Linux – if it returns empty or data , the download was corrupted. It looks like the string "ap3g2k9w7tar1533jpn1tar link" is