During the installation (step 2) I cannot reach 192.168.1.100:4000 via my browser

Check whether you are connected to the "clemapXX" WIFI network or whether the LAN cable is plugged in. Refresh the webpage http://192.168.1.100:4000 and wait up to 30 seconds. Check again that you are connected to the “clemapXX” WIFI network or that the LAN cable is plugged in and try to access the webpage http://192.168.1.100:4000 again. If you still cannot access the webpage, try opening the webpage with another device, e.g. another mobile phone or computer.

Perform a hard reboot by pressing the RESET button for more than 5 seconds (and less than 10 seconds) and wait 3 minutes.