If PHP version 8 or higher does not support SSH2, then it is not possible to establish an SFTP connection using SSH2 with PHP. In this case, alternative libraries or methods can be used to establish an SFTP connection, such as phpseclib or the ssh2 PECL extension. Alternatively, upgrading the PHP version to one that supports SSH2 may be an option, or using a different programming language that supports SFTP connections with SSH2.
