[IPython-dev] Cannot connect to kernel when not using localhost

[Justin]

Hello list,

I recently explored setting up a notebook that I can share over
the web with one other user.

I followed the directions  on 
https://ipython.org/ipython-doc/dev/notebook/public_server.html exactly.

I can access the nbserver from the web but when I open a notebook, I cannot
connect to the kernel, though I do believe the kernel is started since I see

[I 16:00:26.023 NotebookApp] Kernel started: 
a23ba8fa-16dd-41e9-9b60-b1785c872387
in my terminal.

In the notebook I see the error message:

"A connection to the notebook server could not be established. The 
notebook will continue trying to reconnect, but until it does, you will 
NOT be able to run code. Check your network connection or notebook 
server configuration."

I am using ubuntu and ipython 3.0 with the new jupyter notebook.

Note that I can edit markdown and raw text cells, I just cannot execute 
code.

The problem is reproducible in both firefox and chrome.

I do not see this problem when I start the notebook on localhost.

On another note, it takes a very long time (~ 1 minute) for my browser to
connect to https://<myip>.9999/  Not sure if this is part of the issue 
but I thought
it might be useful.

I saw this issue reported before but it was basically for people running 
windows
with antivirus and I do not have either.  I'm fairly certain that it is 
me that is
doing something wrong but I cannot for the life of me figure it out.

Thanks for any input you might have,

Justin