When configuring the CRS make sure that you choose the right network for the public and private connection. If the CRS root.sh scripts hangs during the installation and the error is oac_init:2: Could not connect to server, clsc retcode = 9 then the cause is almost certain a mismatch in the network setting.
Some of the stuff I do for a living. This mainly concerns working with Oracle Databases and Application Servers. Lately I picked up AWS, Azure and OCI.