How to configure 2 routers in one network with DHCP and DMZ?

Question

network hardware

Hello everyone, this is a problem, there are two Netis WF2780 and Netis N2 routers.
Netis WF2780 gets connected via WAN PPPoE and distributes WIFI 2g/5g, Bridge 192.168.1.1, DHCP 192.168.1.2 - 192.168.1.100;
Netis N2 receives 5G WLAN network from Netis WF2780 router, its IP is 192.168.2.1 DHCP 192.168.2.2 - 192.168.2.24;
The situation is this: I need to open the client (home server) port 192.168.1.4 reserved on Netis N2.
How do I make a DMZ for Netis N2 192.168.2.1? It is not reserved, and constantly even with a working DHCP on the Netis WF2780 receives a new IP. Or you need to configure DHCP on the first router so that the reservation of addresses of 2 routers at the point is visible. Tell me how to check this? I am not strong in network administration, please do not be toxic.

In short, the ultimate goal is to open a port for the server, perhaps not one, or just open the DMZ for it.

PS

Answer 1

on the second router, turn off dhcp
, forget about the wan port
, connect it via wifi,
do all forwarding, settings - on the 1st router.
the second you have is just a switch with a wifi port.
all devices will be on the same network