We're in the process of testing the upgrade to version 9.9.6, build 28944. The production server with version 8.2.4, build 18573, was cloned. The clone was given a different name and IP, and VisualCron was upgraded on the clone. The clone is in the same datacenter and subnet, and has the same external facing IP as the production server.
When validating connections in version 9.9.6, four of the connections failed with the same error message "Connection lost due to error 96258". All four connections are of type "SFTP (SSH - Secure Shell)". Those four connections succeed in version 8.2.4. Nothing in the connections was changed. Several other connections succeed in 9.9.6.