First, make sure the listener on database server (computer A) that receives client connection requests is running. To do so, run lsnrctl status
command.
In case, if you get TNS:no listener
message (see below image), it means listener service is not running. To start it, run lsnrctl start
command.
Second, for database operations and connectivity from remote clients, the following executables must be added to the Windows Firewall exception list: (see image)
Oracle_home\bin\oracle.exe - Oracle Database executable
Oracle_home\bin\tnslsnr.exe - Oracle Listener
Finally, install oracle instant client on client machine (computer B) and run:
sqlplus user/password@computerA:port/XE