Was this issue ever resolved? I'm experiencing a similar issue (on 6.4.4.16) where packet capture shows the first FTP SYN packet that the client sends isn't being ack'd. The client retransmits the FTP SYN 3 seconds later, receives the ACK immediately and proceeds with the FTP login and transaction normally. This happens every time with every client. The issue does not present when the client is hard-wired into the same VLAN (same client IP). Furthermore, we don't see this issue at other sites that hit the same FTP server, even those that cross the WAN (in the problem scenario, the FTP server is local to the site). So we do not beleive this to be a problem with the server...appears to be a single-site "wireless" issue.