Setting Up 3 Network Printers Connected To An Old Router That Is Connected To A Modem / Router Combo Using Ethernet

I am trying to setup 3 network printers for a client.

He has an Xfinity modem / router, and there is only 1 free ethernet port available on the router.

To avoid buying a switch, I used an old router he had lying around.

I plugged in the 3 network printers into ports 2, 3, and 4. When plugging the WAN port from the old router to the empty port on the Xfinity modem / router none of the printers show up on the network. A single device does show up as a connected device in the Xfinity admin settings.

When I remove the connection from the old routers WAN port and the empty ethernet port on the Xfinity modem, and plug that into port 1 on the old router, 1 of the network printers shows up. So the Xfinity router empty ethernet port is plugged into the old routers port 1. The 3 network printers are plugged into ports 2, 3, and 4, but only 1 of those printers shows up to add in Windows.

It doesn't seem to matter which order I plug these in, still only 1 shows up.

Is there a solution to get all of the network printers to show up?

When you want to use a old router for this. You are essentially going to be using it for the built in switch. In the routers config, disable the firewall/spi security and additionally disable dhcp. Put it's local IP address statically in to the subnet you want it connected with. I.e if the first router is at 192.168.1.1 /24 you would put the second router at 192.168.1.254 /24. Then connect the Ethernet to the lan side of both routers. You can now use it as a dumb switch.

Note: depending on the age and models of routers, you may need a t568a/t568b crossover cable.