Hello @Mugros and welcome to the forum!
It’s working fine here, changing port to 220 on the SFTP server, then on Duplicati, then running the backup.
That’s the Backup destination portion of the job’s Destination screen. There’s a Test connection button too. What happens when you press it, and how quickly does it error? If it’s still the timeout, netstat -an could show what’s going on, in terms of what communication is being attempted where, and how far it proceeds.
You could pipe that into find if it makes things easier to spot. I assume this is Windows, if you run PuTTY (which is not an SFTP client, but its relative PSFTP is, and testing all the way through sftp may be helpful).
You could also go to the job’s Commandline option to see if the Target URL looks reasonable. An example:
ssh://localhost:220/the-backup-name?auth-username=xxx&auth-password=yyyr&ssh-fingerprint=zzz