Thank you @drehb. I'm a noob when it comes to things like this.
In the terminal I get the message:
E 17-04-07 10:38:15.580293 Failed to Bootstrap: (FailedExternalReachability) Bootstrappee node could not establish connection to us.
I 17-04-07 10:38:15.581296 Bootstrapping(41f597..) Failed to bootstrap. Terminating.
So, I guess that it can´t get through the router.
In the router there are only three settings for UPnP:
UPnP Enabled: ON
Secure Mode Enabled: OFF
Anything else I need to consider?
Otherwise I will see if I can learn how to port forward