Many people seem to think this it is possible, yet clearly in this document the boundary is stated as inter-process which to my mind means "no network".
Another document is completely unambiguous:
The named pipe transport has very little reach; it can only connect to services running on the same machine
So why are so many posters here saying it can work?
In general, named pipes work across the network. However, using named pipes with WCF, you're restricted to on-machine communications. That's why your first and last links are both correct.
I think you need to make a distinction between Named Pipe and WCF binding implementation NETNamedPipeBinding.
The NetNamedPipeBinding is a predefined binding for WCF for on-machine communication.
Provides a secure and reliable binding that is optimized for on-machine communication.
But if you check the MSDN documentation about Named Pipes, you can see that it is possible to setup a named pipe across network.
Named pipes can be used to provide communication between processes on the same computer or between processes on different computers across a network