what could be the problem when you cannot contain a machine in network?
There is a known issue in Endpoint 184.108.40.206 where containment fails to work.
Reference: RSA NetWitness Endpoint 220.127.116.11 Release Notes - https://community.rsa.com/docs/DOC-94369
Please upgrade to at least Endpoint 18.104.22.168
Other things to consider if Containment still doesn't work.
Reference: RSA NetWitness Endpoint 4.4 User Guide - https://community.rsa.com/docs/DOC-81665
In the Endpoint UI, Machines, check that the machine you wish to contain is not showing as having a Driver Error Code problem. The Endpoint Agent software must be fully functioning.