Cannot connect to newly installed Firewall Home Edition

Hi

Something seems not to work at me.

My environment:

• Hardware Sophos XG 115 Rev. 3, Harddisk updated to a 256 GB model
• SFOS-Image SW-21.0.0_GA-169
• Could install, initial boot properly made
• Screen now at System Detail, list of hardware, then password: with blinking cursor
  -> Funnily keyboard does not react anymore at all
• "Status"-LED at firewall is blinking (a bit faster than once a second, but not really fast)
• A pc is connected to LAN-port, lights of NIC is green and orange flashing

So far, everything seems to look good for me - Now comes the mystery:

NIC of PC is configured: 172.16.16.15/24, no GW, no DNS. Other environemt notes for PC:
* No other connections are active
* Firewall is switched off
* Browser Firefox under WIndows 11

When I now try to connect to https://172.16.16.16:4444 as per Installation Guide for Firewall Home Edition, I only get a timeout. I cannot ping the ip - which can make sense, but don't know, how it should be - no idea, what is going wrong :-(

Thank you for any further help!