Hi Hongxu,
Shortly after responding to your thread, I tried something different and with very little doubt, but surprisingly it worked. So on my new Linux VM from the AWS cloud, there is no DNS so when I registered the trusted host, I used the server IP address of my policy server rather than the server host name. I compared the SmHost.conf file of this new web agent to the many web agent hosts on our on-prem environment and the only difference is the policy server host entry.
So I modified the /etc/hosts file on the AWS VM and added IP address of the policy server and then modified the SmHost.conf file to use the policy server host name rather than IP addres - - > policyserver="ps.company.com,44441,44442,44443" then restarted Apache and amazingly it worked!
This solved my issue, but I am still curious why it would complained about the IP address rather than server host name for the policy server.