> PING[ARC0]: Heartbeat failed to connect to standby 'PFSTD'. Error is 16058.
ORA-16058 is "standby database instance is not mounted". Startup mount your instances. Since this is a RAC standby:
srvctl start database -d standby_db_name -o mount
>2. Start the instance 1 on node 1 as:
> startup nomount
For RAC, you should not be using SQL*Plus to start/stop your instances. You should use srvctl instead.