Connect to FTP/SFTP in Dolphin or transfer Nautilus Bookmarks

On the left hand side of the Dolphin window, click Network. There will be a item for adding a network location like ftp or scp. Dolphin is a great file manager...

If you just want a quick connection, you can click the navigation breadcrumbs on above the file list (or Ctrl+L) and type directly:

sftp://{username[:password]}@{domain}/{path}

SFTP in Dolphin is implemented as fish

fish://{username[:password]}@{domain:port}/{path}