It could be possible you will be able to get into the server using filezilla and the IP of the computer is also not blocked.
When trying to connect to a SFTP server using UiPath activities we get the following error when testing connection: An established connection was aborted by the software on the host machine
Request to update the same package to the latest 1.0.6710.16240 version
(Note , while writing the article the latest available version is 1.0.6710.16240, you may change to any of the latest version newer than the mentioned one )
For upgrading select the version -> Update -> Save
Also, you can download the package from the below location (offline):
Location to be placed in :
C:\Program Files (x86)\UiPath\Studio\Packages
Now -> Manage Package -> FTP Activity package -> Update to the latest version.