Cannot reach the dashboard of openhabian of raspberry

Everything seemed ok with all items and so on.
But when i rebooted my raspberry with openhab i cannot reach the dashboard on adressofpi:8080
all other things work well. so i can login into openhabian and there is no error
and i see the openhabian from may mac with the same pi address.
what could be the reason that i cannot go to the dasboard.
that is also the reason why it is offline in the cloud.
thank you for help
bernd langner