socket.error...but changing port didn't help, nor did reboot

[noequus]

I installed and played with SIP for a while (I like it) but now I cannot get it to run, with this error (full terminal text below):

socket.error: No socket could be created -- (('::192.168.1.15', 8666, 0, 0): [Errno 99] Cannot assign requested address)

As you can see I changed the port (tried several). Also tried stopping the service and status with systemctl:

pi@192.168.1.15:~/SIP$ sudo service sip stop
Failed to stop sip.service: Unit sip.service not loaded.

pi@192.168.1.15:~/SIP$ systemctl status sip
Unit sip.service could not be found.

Thanks for any thoughts!
Gary

pi@192.168.1.15:~/SIP$ sudo python sip.py
Messge from Signaling plugin!: Just an example!
plugins loaded:
  mobile_app
  plugin_manager
  signaling_examples
  system_update
zones changed
Starting timing loop

[0, 0, 0, 0, 0, 0, 0, 0]
http://::192.168.1.15:8666/
Traceback (most recent call last):
  File "sip.py", line 291, in <module>
    app.run()
  File "sip.py", line 219, in run
    return web.httpserver.runsimple(func, (ip, port))
  File "/home/pi/SIP/web/httpserver.py", line 178, in runsimple
    server.start()
  File "/home/pi/SIP/cheroot/server.py", line 1820, in start
    self.prepare()
  File "/home/pi/SIP/cheroot/server.py", line 1779, in prepare
    raise socket.error(msg)
socket.error: No socket could be created -- (('::192.168.1.15', 8666, 0, 0): [Errno 99] Cannot assign requested address)