Seems to me that there are number of things that you should configure for your setup to work properly:)
1. On your 3000 appliance is the interface labeled "Mgmt" I suspect that you have used it for initial configuration of the appliance. Please connect your laptop/management PC to it.
2. Configure static IP address from the range you were previously getting from your router on eth0 (i.e. 192.168.1.2 with the gateway being the that of your router, i.e. 192.168.1.1)
3. You will be better-off using firewall's built-in DHCP server, instead of passing-through the DHCP requests to your router, so I suggest defining another network for internal scope (i.e. 192.168.2.0/24) and assign it to your eth5.
4. For DNS, I suggest using 9.9.9.9 (IBM quad9 secure DNS server that is marginally better than Google's in terms of privacy)
5. Now, create the outbound rule permitting network 192.168.2.0/24 to access the Internet.
6. Once connected, enable security features such as IPS, AV, Antibot, etc... and configure their automatic update schedule.
Cheers,
Vladimir