What is the OS of Server B? Did you try to re-install the latest remote agent on this server and do a reboot after the installation?
I have done everything you instructed, both installed Server 2012 and Verista 21
https://www.veritas.com/support/en_US/article.100017208
Check that the ports are configured correctly.
I would suggest for a test to turn off any firewall rules and antivirus rules on the BE server and remote server and trouble-shoot from there.
Also, make sure trust is established.
https://www.veritas.com/support/en_US/article.100026457
