Sounds like WinSCP is connecting to the node fine. So you don’t have a port or password issue.
If you are logging in with username repeater you do not have permission to edit any files in /etc/asterisk. You need to login with username root but the root user is not allowed to ssh by default. It is possible to allow root ssh but I’m not sure how folks using WinSCP handle that.
Would any WinSCP users like to shed some light on this?