connect to new user within PDB not working

Oracle 18c

Connecting to PDB as 'sys', I cannot figure out how to connect to a schema other than 'sys'.

Here is what I have tried after logging into Oracle 18c CDB as 'sys':

ALTER SESSION SET CONTAINER= PDB;
conn myschema/mypasswd

--and also tried right from CDB

conn myschema/mypasswd@PDB;

Both approaches fail to get me connected as 'myschema' within the PDB.
Any suggestions?

The issue was that the tnsnames.ora file had an incorrect HOST ip address for the tns alias.
All the SQL in the initial details now works as advertised.