Unable to register host on rancher - ERROR: is not accessible

I am a newbie on rancher and I am trying to run it on my laptop:
Ubuntu 16.04 64-bit
X-Rancher-Version: v1.5.1
Docker version 17.03.0-ce, build 60ccb22

I get the following error:
ERROR: is not accessible
ERROR: Could not reach Giving up.

I have tried to follow along on some of the discussion with a similar problem.

I have also defined the following rules in ufw
500/udp ALLOW IN Anywhere
4500/udp ALLOW IN Anywhere
4789/udp ALLOW IN Anywhere

Unfortunately I have not be able to succeed.

The hosts you are adding have to be able to reach the Rancher server URL through port 8080, you can try curl from the commandline to retrieve why this isn’t working.