How to configure separate operation of LAN interfaces through one WAN interface?

Question

Computer networks

There is a Mikrotik router. The Internet comes to the SFP port.
Eth1 should pass traffic without processing directly to the Internet, it will have a 2L switch with connected hosts that have static addressing in the required range.
Eth2-5 should be behind NAT, with its own addressing and firewall settings, but at the same time have access to the main network and directly to the Internet.
In the SFP router, the interface and eth1-5 are combined through one switch module.
How to implement this model? What to think about?

Answer 1

eth1-5 connected via one switch module

Connect eth2-5 and configure. Then configure eth1.

Answer 2

SFP port and eth1 to the bridge, on the bridge, and hang the address of the microt for NAT clients
eth2-5 in the second bridge and put them on health.