Before connecting, make sure it is like this in the settings
Pay attention that often after you turn off the FZ debug level becomes 0
so it is necessary to set it to 2 again before the connection.
Is that connection related to this hosting or not?
When you used it, did you see the hosting content (files) in the right window (server) ?
Have you ever successfully connected via FZ to ftpupload.net ?
When you started FZ for the first time and connected to ftpupload.net, did it ask you something about the certificates and did you approve it?
Have you tried to install the latest version of FZ (in case you have one with a bug) ?
Other