@sgventureslab you mentioned your router’s IP address is 192.168.10.74 but it looks like that is also the IP address for the box, is that right?
It seems odd to me that your router and Freedombox would share the same IP address. Did you set it up that way intentionally? I’m not very experienced with networking or anything, but I guess what I would expect is your router to assign an IP address to the box with DHCP.
Does your router have a web interface? That broken web page you are getting reminds me of an issue I had after I set up Pihole on the box, and Pihole and Freedombox were both trying to broadcast to port 80 on the same IP address.