manage.py runserver
I had the same problem and  here was my way to solve it:
First, You must know your IP address.
On my Windows PC, in the cmd windows i run ipconfig and select my IP V4 address. In my case 192.168.0.13
Second as mention above:  runserver 192.168.0.13:8000
It worked for me.
The error i did to get the message was the use of the gateway address not my PC address.
I am running python manage.py runserver from a machine A
when I am trying to check in machine B.  The url I typed is http://A:8000/ .
I am getting an error like The system returned: (111) Connection refused