For a demo, I'm trying to set up a base deployment of ArcGIS Enterprise 10.5.1 on a standalone virtual machine using the ArcGIS Enterprise Builder. The ArcGIS Enterprise Builder configuration failed when configuring the web adaptor for the portal. Through trial-and-error, I've been able to successfully configure the ArcGIS Server instance and its web adaptor, including SSL via a self-signed certificate.
However, I'm still experiencing problems getting the Portal configured. For one, I can't figure out how to properly configure the Portal to work with a self-signed certificate. Most importantly, however, I'm not having success configuring the Web Adaptor to work with the Portal. When I try to configure the Web Adaptor to work with the Portal, I'm just specifying the machine name (i.e., http://<machine-name>:7443), since it's not on a domain, but I get an error indicating that I need to specify a fully-qualified domain name for the Portal. Then, I came across this part of the installation documentation, which seems to suggest that the portal needs be on a domain. So, is it even possible to configure portal to work on a machine not connected to a domain?