FreeBSD ftpd onlu allowed one connection then times out for new attempts

I configured ftpd (running as a daemon - ftpd -D) yesterday. I connected just fine from my slackware system and transferred some config files. When I realized that it skipped my zsh config files, I did another ftp. But this one, and all attempts since then, fail with a timeout. No logs left in anything in /var/log at all.

So I killed it and added -d for debugging. Still no logs. I verified with a ps that ftpd was there and running.

I WAS, however, able to connect internally (i.e, localhost to localhost), just not from my slackware system.

I just ran another test using AndFTP on my cellphone. It connected instantly and after authentication, I was in. Repeated attempts from my cellphone continue to work.

So, it appears that there's an issue between my slackware and FreeBSD systems that happened after the first connection.

Does anyone have any idea what could be going on?

Thanks.