How does one connect to a schema within a PDB (other than schema SYS)? Using Oracle 18c on RedHat Linux 8

Connecting to CDB as 'SYS', I cannot figure out how to connect to a schema within the PDB other than as 'SYS'.  Maybe I don't understand the CDB/PDB architecture well enough.

Here is what I have tried after logging into the Oracle 18c CDB as 'SYS' (using sqlplus sys as sysdba):

ALTER SESSION SET CONTAINER= PDB;
conn myschema/mypasswd


and I also tried (right from the CDB)

conn myschema/mypasswd@PDB;


Both approaches fail to get me connected to the schema myschema in the PDB.  That is, I am still 'SYS' in the PDB. 

Are there any suggestions/explanations on how to resolve this?
Do I have to setup some kind of access from the CDB-to-PDB for the schema myschema?
Turns out there was a typo error in the tnsnames.ora file - the HOST ip address field was invalid for the system in question. 
Example below (values have been anonymized for security reasons)

PDB =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 10.10.1.11)(PORT = 1555))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = PDB)
    )
  )


The file was probably copied from another server (as a template) and the HOST ip never updated.

Given the above, the correct way to connect would be:

conn myschema/mypasswd@PDB;