Maximum Queue Connections

I'm uploading to an FTP server (ProFTP) which has a limit of 20 concurrent connections using the SmartFTP queue. I had the queue set to use 15 workers, but I started getting failures and was unable to connect from the remote browser pane either. The server logs show very large numbers of Max instances reached, New connection denied errors.

I've tried turning the queue down to six and then one worker, but this hasn't helped. There are no other users connecting to the server.

The only thing I can think of is that SmartFTP isn't reusing connections (it's set to), but is instead abandoning them without logging out and opening new ones - is this possible? After a while after throttling back to one worker I'm able to connect to the server again, which I think is the 'abandoned' connections reaching the server session timeout.

Hello ..

Your assumptions are probably correct. Your FTP server may not recognize the disconnects because your connection goes through a firewall/proxy.
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SmartFTP