ProFTPD won't auto start on inetd mode

I was using ProFTPD in standalone mode for a while and usually got a problem ProFTPD crash or shutdown occasionally.

So I switch to inetd mode and those problem gone.

However, I got new problem. After I restart my server, I will not able to connect to FTP. I have to switch ProFTPD to standalone and manually start ProFTPD once before switch back to inetd to get it work.

I’m using Ubuntu 14.04 32bit on DigitalOcean