FTP TLS connecting very slow

I have an FTP site on our server. I have been using FileZilla. FTP and FTP with TLS work fine.

DO however there is an issue. With normal FTP it works. With FTP with TLS, it takes it several minutes to connect and finalize things. This does not occur with FileZilla.

It is making DO unusable for FTP to our primary site as we cannot use non TLS for production work. Are there DO logs for FTP that I can check for the connection time?

Yes, accessible via the FTP menu on the default toolbars. This guide explains how to turn on the log (as well as additional debug logging, if needed), and other things that are sometimes worth a try (depending on what the log shows is happening):