You can have below checks -
1. Check if the port if open using "$netstat -taupen |grep <port>"
2. Check if iptables and selinux are off.
I will request to open a new question on HCC to track you issue.
Please try by restarting ambari server or your sandbox.
$ ambari-server restart
$ init 6
then check ambari server status.
if still you are not able to login then paste /var/log/ambari-serevr/ambari-serevr.log here.
First i have successfully login to ambari-sever but when i try to add an other "Node" into cluster. then it give me this error.