The issue is, on Ubuntu, FileZilla is trying multiple ssh keys even when set to use username/pass for sftp connections. This causes WPEngine to drop the connection after the first one or two attempts with bad keys.
To fix this, we can set the SSH_AUTH_SOCK
env variable before launching filezilla. This does require opening FileZilla from the cli, but we can make an alias for it.
In my .bashrc
file, I add this alias at the end.
alias fz="SSH_AUTH_SOCK=null filezilla &"
Now the cli command fz
will open FileZilla and work as expected.