Can't connect through FPP Proxy

[JFGray]

I've had this setup (F16V4 controller, FPP on Rasp Pi4) running wired to ethernet, so I know the components are setup.  I ran the Ethernet cable to the F16v4 and then a jumper to the RPi4 - so both hit my router directly.

But I don't have wired ethernet where my controller needs to be, so I'm trying to setup the FPP for wireless connection to my LAN and as a proxy for the F16v4.  So I want to run wireless to the FPP and let the FPP talk to the controller locally via wired ethernet.  The FPP shows up on 192.168.1.214 as it should and is fully available wirelessly.  The F16v4 is connected by a short jumper using the left Ethernet connector to the FPP/RPi4.  It is statically set to 192.168.1.216.  When I get on my laptop and address 192.168.1.214/proxy/192.168.1.216 I get a "503 Service Unavailable" error.  

Why?  I can't figure out what is wrong.  The RPi certainly isn't busy.  When setting this up I had initially left a wired connection to my router connected to the other Ethernet port on the F16v4 - as I had it originally wired - and with that wire the proxy connection did work.  That left me even more confused.  What am I missing?

[JonD]

Looks like you are trying to use the same IP address range for both networks.  You need to use two IP ranges.

Home Network 192.168.1.x
Set the FFP RPi4 wireless to IP:192.168.1.214 SN:255.255.255.0 GW:192.168.1.?(Home Internet Router)

Display Network 192.168.0.x
Set the FFP RPi4 Ethernet address to IP:192.168.0.1 SN:255.255.255.0 GW:NONE/BLANK
Set the F16v4 to IP:192.168.0.2 SN:255.255.255.0 GW:192.168.0.1 (GW=IP of the FPP ethernet interface)

[Poporacer]

Like @JonD mentioned, having both interfaces on the same network can cause problems (an interface is a network adapter, not thedevice itself, so the Raspberry Pi has 2 interfaces)
This video might help.