I found the same thing happen on vsftpd aslo, although not that frequently.
When downloading small files from remote vsftpd ftp server, which is far away with relatively long link delay.
The "226 transfer complete" might come later than data socket close because of link delay. Whenever this happen, flashfxp will lost control connection for small files downloading. If "226 transfer complete" comes before data socket close, flashfxp is ok for small files.
It seems flashfxp is always expect "226 transfer complete" before data socket close.
Is there any fix for it ?