A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond: We were unable to connect to the server.
Check and ensure that the server is up and running. If it is possible to connect to the server from the internet, this may have been an intermittent network problem. Submit the mailbox in Retry Mailbox Migration Errors mode after the mailbox has successfully migrated.
For Google migrations, this means that IMAP is disabled for either the account or the entire tenant. You will need to enable IMAP access for MigrationWiz to connect.