In version 8 red hat introduced some major overhauls to their security and cryptographic components. (Documented Here) Most notably with relevance to earlier versions of Datastage (which require TLSv1) TLSv1 is disabled by default. If you are encountering very obscure TLS errors then it may be worth running the following command to see if it is causing the issue.
update-crypto-policies --set LEGACY
Now restart the server workbench is running on and see if this command has fixed your issue.