I've run into issues trying to use the same web adaptor for both Server and Portal. What I recommend doing is installing the web adaptor a second time and configuring it for Portal. So you would have one web adaptor for Server, and another for Portal.
Did you do the federated server or the hosting server or the federated WITH hosting server setup?
I'm seriously considering the federated WITH hosting as we have the space and servers.
Also, we have three servers...
A DMZ with our Webadaptor installed that stores and publishes our external maps.
Two internal clustered servers that are our ArcGIS Server setup and store and publish our Internal maps.
I'm not sure where I would setup Portal? On the DMZ since we need it to allow public access or can Portal communicate with the DMZ Webadaptor and manage that for us...?
I've done both options. If you have the space and servers, I would recommend federating with a hosting server. I feel this option makes it easier to provide content to your organization with less steps.
If you plan on sharing data with the public, I usually recommend using ArcGIS.com for public content, and Portal for internal content. However, if you want to use Portal for public content, that option is available. The web adaptor for Portal should handle the requests and send them to your Portal instance on which ever server Portal is hosted on. I would recommend installing Portal on the more powerful server since it requires a good amount of CPU and RAM.
What I am hoping is that...
With Portal installed an Internal requestor goes to Portal and searches for their map. Finds it. Consumes it as needed. An EXTERNAL requestor goes to Portal, can ONLY see the PUBLIC ACCESSIBLE maps / Gallery and Consumes IT as needed. If an EXTERNAL requestor were to 'somehow' get the URL to an INTERNAL REST SERVICE the WebAdaptor/Portal would make that URL invalid to them...
Also, I'm hoping I don't have to shut down a Production Server (or even reboot it) to Install Portal and configure it... I need to be able to set it up without any downtime for the live maps already running.
I'm really looking forward to getting Portal running and using it LOCALLY like I have been able to use ArcGIS Online through the net.