Access control in external storage

hello , i connected an external storage via SFTP to my nextcloud ,

i made 2 users => user1 , user2

user1 can see files that uploaded by user2 in external storage and user2 can see files that has been uploaded by user1

i want that each user only could see his/her own files ( just like the local storage ) …

what do you suggest :?

as a workaround i was thinking about mounting the external storage as a folder in the os and using it as a data path for nextcloud … ( How do you use multiple HDDs in Nextcloud? )

do you think this way will solve my problem :?