I have two NICs. I want NIC A to be used and have set it as the preferred network interface.
Remote Access Private IP Address ignores my wishes and binds to NIC B’s IP Address.
Manual specification of public port is OFF, so Plex is in control.
I have restarted, rebooted the server, hopped on one foot whilst scratching my belly, etc.
So you may want to manually specify a port to ensure Plex Media Server is able to use the interface you have configured. If you do this, you’ll also have to manually configure the port-forwarding rule on your router.
Also make sure that the interface to which you’re attempting to have PMS bind:
Has Internet access.
Has a valid default gateway assigned.
Has valid DNS servers assigned.
You may also want to ensure that it is the “primary” interface Windows uses for off-network traffic by setting its interface metric lower than the undesired one. You can see which interface has a lower metric (and is therefore primary) by issuing Get-NetIPInterface from PowerShell. To set an interface’s metric, use Set-NetIPInterface -InterfaceIndex x -InterfaceMetric y, where x and y are the interface index returned by Get-NetIPInterface and the new metric, respectively