Need to maintain a long connection

Long connections often exit

It takes a long time to reconnect every time

Especially for servers with slow network speeds

Always waiting for a long time on this interface

Need to maintain a long connection
Even if it wastes network resources

Did you try to enable keepalives?
https://winscp.net/eng/docs/ui_login_connection

I regularly maintain SFTP connections for several days and even weeks. If keep alive doesn't work I would assume your ISP or the fact your connection is bad is the culprit.