Got the same problem here.
Wanted to try the openhabian with fresh installation, but not possible to connect from another computer.
I can also ping the raspberry, everything seems to be running ok but I have a “ERR_CONNECTION_REFUSED” when trying to loaded the page.
Also try to update and upgrade all packages, without any improvement.
Finally, tried to follow the instructions on that page : openHABian hassle-free openHAB Setup
so used
sudo mv /boot/config-reinstall.txt /boot/config.txt
sudo reboot
But since the raspberry is not able to boot properly.
Will try tonight to do a full reinstal of the openhabian.