My LAN does not work anymore if i connect Endian Firewall

Never connect Endian Firewall multiple times on the same switch if you did not configure it yet using the network wizard.
After installation Endian Firewall connects each network interface within a bridge in order to easily access the web interface without need to search for the correct green interface.

The device acts like a switch if it is not configured yet, which causes a loop within your LAN if you connect it multiple times to another switch.