Anyone can provide some insight if the "sys" user can log onto a remote server as sysdba?

Our environment has a primary server (odajc) and a physical standby server (odacs) running dataguard to keep them in sync.

From the primary server, we can log into odajc using the sys id without problems.

However, when we try to log into the physical standby (odacs) from odajc using the sys user, it will always point back to the primary servere - odajc. Below is the detail:

The reason why we try to figure this out is we cannot get a clean dataguard "switchover". We suspect it may has to do with the sys id not able to log onto the physical standby from the primary server. Thanks in advance!