I can't access services through my Centos 6.9 Web Adaptor. Although the Web Adaptor configuration worked, trying to reach the REST directory fails with "Could not access any server machines. Please contact your system administrator." Firewall rules are the same for the Centos server as they are for a Windows server with a working Web Adaptor on it.
I can hit the tomcat page, but not the rest services directory. Running 10.5.1. The ArcGIS server is Windows 2012 R2.