FTP unstable/slow DOPUS only

[Leo]

@Ironhand

To say it short: It is very slow and also unstable.

Unstable in what sense? That can mean several things so we need more context to understand.

Slow in which circumstances? Lots of small files? Large files? LAN server? Internet server? What speeds are you expecting vs what you get? Is FileZilla transferring multiple files at once but doing each one around the same speed as Opus?

@Ironhand

Does someone have some tips on how I can search for errors or change some settings which might do the trick?

Have you looked at the FTP FAQ? That includes information on how to open the FTP log for more detail.