FYI - I use Dato+Jupyter on on EC2 on a daily basis, so I can vouch that it works. I remember having a similar problem that was cause by 1) not having Jupyter automatically started at boot, 2) the Jupyter config not allowing remote connections.
My suggestion is first check that jupyter is working by ssh'ing into the server and
- Check the jupyter process is running, i..e, ps -ef | grep jupyter
Run a local browser on the the EC2 instance and connect to Jupyter locally. You may need to install links or lynx ( depending on your O/S) so you can do this.
sudo yum install links -y
If this connect then jupyter is working ok and it's either the port is closed (which you said you had checked) or Jupyter config is preventing remote connection. .
If I remember correctly, you edit the file ~/.jupyter/jupyternotebookconfig.py and edit a few parameter. I think the key one is
c.NotebookApp.ip = '*'
c.NotebookApp.port = 8888
how I did not take notes on what I did so this is a guess based on looking at my config file.
If you read these notes it says
By default, a notebook server runs locally at 127.0.0.1:8888 and is accessible only from localhost. You may access the notebook server from the browser using http://127.0.0.1:8888.
and here it talk about how to set up access by a remote web server. I did not bother setting certfile, keyfile or password.