Cannot connect via firefox to as raspberry pi 4 with: http://homeassisant.local:8123

After installing Homeassisant on my Raspberry pi 4:
https://github.com/home-assistant/operating-system/releases/download/9.4/haos_rpi4-64-9.4.img.xz
Flashed with Balena Etcher to sd card

The Raspberry is connected via an ethernet cable to the (wifi)router.
I connect to http://homeassistant.local:4357 (Observer URL) via Firefox on an Ubuntu laptop connected via Wifi.
Result:

Home Assistant observer

Supervisor: Connected
Supported: Supported
Healthy: Healthy

That seems ok, but then i try to connect via homeassistant.local:8123 (Home Assistant URL) i get no connection.

Any tips?

Instead of homeassistant.local i tried it with the ip-adres of the pi but also no result.