Finding and using IPFire behind a switch

I have this setup:

modem (AP) -> wifi -> IPFire (AP) -> eth -> desktop
                      |
                      wifi -> phone, tablet

I want to have this setup:

modem (AP) -> eth -> switch -> eth -> IPFire (AP)
                      |                 |
                      eth -> desktop    wifi -> phone, tablet

I tried it, and my desktop could only find the modem. My phone and tablet had no problem finding IPFire's access point (AP) though.

Any ideas?

Finding and using IPFire behind a switch

Needs more detail. What are you trying to accomplish? I assume the IPFire(AP) is some appliance computer running IPFire linux.

Your original setup all devices are on the LAN side of the IPFire device and can "talk" to each other.

In your desired setup by default IPFire is acting as a firewall so the desktop is on a the "WAN" side of the firewall and isolated from phone and tablet which is on the LAN side. The desktop can find the IPFire IP address by looking at the attached devices on the MODEM or by running a nmap scan.

What I don't like about the current setup is that IPFire is getting its Internet access from the modem over Wifi. I want it to use the Ethernet cable instead (and configure the modem to deny wireless access completely).

But I also want the desktop to connect to IPFire over Ethernet (and configure IPFire to deny admin rights to wireless cients).

So I would have to have two Ethernet ports on the notebook that runs IPFire (assuming IPFire would handle this accordingly), which I don't have.

So I am basically trying to use the switch as some kind of splitter/adapter for the one Ethernet port. I don't know if that is possible.

In case it's still not clear, I use the switch and the desktop interacts with the Internet directly through the switch only, and I want all desktop interaction with the Internet to be mediated by IPFire, which is also connected to the switch. I want IPFire to take over.

Doesn't the laptop have a cat5 and a wi-fi connection? Aren't those your "two Ethernet (read: networking) ports"?
Can't you just connect as you do now, but change the connection between the Modem and the IPfire to wired?

modem (AP) -> eth -> IPFire (AP) -> eth -> desktop
                      |
                      wifi -> phone, tablet

And then do as you describe...disable wi-fi on the modem and manage all connections with the IPFire appliance. No switch required.

What am I missing?

Your diagram shows two ethernet ports on the laptop. The OP needs a USB ethernet adapter for to work. I assume the OP wants all devices behind the laptop firewall.

Originally Posted by michaelk Your diagram shows two ethernet ports on the laptop. The OP needs a USB ethernet adapter for to work. I assume the OP wants all devices behind the laptop firewall.

Doh!

Originally Posted by michaelk Your diagram shows two ethernet ports on the laptop. The OP needs a USB ethernet adapter for to work. I assume the OP wants all devices behind the laptop firewall.

Your assumption is correct. I want all devices behind IPFire's firewall. Besides, I want Ethernet connections from the modem to IPFire and from IPFire to the desktop. That's why I won't just use the one Eth port to connect to the modem and have the desktop go through IPFire over Wifi.

I thought of buying a USB to Ethernet adapter, but I had this switch lying around doing nothing so I thought I should try it.