A bad idea? Daisy-chaining modem and router with the same ip numbers

[Steve G.]

I have a practical situation that might use some advice. I am not near the
equipment, so I can't manually change IP addresses on the machines, and the
server does not have a GUI, so my wife can't fix it either.

The question:

if I take a modem that runs the LAN as 192.168.1.1, and plug into one of
its ports a wireless router ALSO running as 192.168.1.1, would I bring down
the Internet or cause other types of horrible harm?

The background:

I had a home network with a modem and a wireless router. The router plugged
into one of the 4 open ports in the modem, and several computers, including
a server and two desktops were connected into the router. No computer was
connected to the modem.

The wireless router network was 192.168.1.x. - the server and linux box had
fixed addresses, outside the DHCP range. I don't remember the IP of the
modem, but it was (I think) using the 10. range for the local network. I
used the interface of the router to relay ports 80, 23 (or 22, the one for
ssh), and some other to the server or desktop. I don't have access to do
the same through the modem.

Long story short, the modem needed replacing and the new modem is running
on the 192.168.1.1... network. The desktops are now connected to the modem
directly. The router has been reset and switched to 192.168.2.1

The fixed IP desktop is fine, because the new and old networks are the
same. The wireless devices are fine, because they run on the new network
and get the IP automatically assigned. But the server is out of each, as
its address is 192.168.1.190 and it is connected to a router with the
network 192.168.2.x

So I am thinking what might happen if I change the router's network back to
192.168.1.x - would it work?

Thanks in advance.
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