Appears to have received TCP RST instead of logon handshake.
Did the hostname/COP resolve to a correct IP for one of the database nodes?
I think so.
From Client A, I can ping both alves.corp.xxxx.com and alvescop51.corp.xxxx.com.
Even if I use IP address directly in the JDBC, it has the same error code.
Yes, we have seen this kind of exception before. It can be due to a networking problem. If you are a Teradata customer, then please open an incident with Teradata Customer Support.