I'm trying to use my RPI3 in order to read datas from ethernet communication and send them over wifi to a remote FTP server.

I've been able to connect my RPI3 to internet via wlan0 so far, however I've had troubles configuring the eth0 part of the network.

Diagram of the "issue"

My problem mainly revolves around how I should handle eth0, I've read that in order to avoid issues I shouldn't use the same IP address as wlan0. But if I do that what adress should I put in eth0?

I might add that for software reasons I can't use DHCP to allocate addresses automatically, I can however change the connected device adress and gateway if I have to bring him back on the same subnetwork as wlan0.

Second strange point, when I add an IP route via "sudo ip route add" ways, it disappears upon reboot. I thereby tried to add it in static through DHCPCD.conf but it doesn't show up in ip route.

Here are both IP route and DHCPCD upon RPI3 reboot:enter image description here

enter image description here

Thanks in advance

  • 2
    Do NOT post illegible pictures - post text.
    – Milliways
    May 28, 2021 at 12:20

1 Answer 1


The connected device on the wireless network is already in a different subnet than the wifi router, so you can't use the same IP on both interfaces, because it would be in the wrong subnet.

The easy answer would be to configure the port for dhcp and let the network pick an address. But if you don't have a dhcp server on the subnet or have to manually configure it, here is what I would suggest.

Since you are using on the wifi network and your connected device on the wired network is using subnet 192.168.15.x, then a good candidate would be But you could use any free non-conflicting ip address on the correct subnet.

  • possible to have different subnet masks to let a device have the same ip on two adapters configured with different subnet masks. (for example on both 192.168.x.1 and 192.168.1.x) routing would direct to appropriate adapter based on the other device's ip. most people probably don't need to play with that though.
    – Abel
    Jun 27, 2021 at 15:55
  • This doesn't fit the existing network configuration in the original question, and this non-standard use of netmask is highly irregular and likely to break.
    – user10489
    Jun 28, 2021 at 0:35
  • it fits your answer. "you can't use the same IP on both interfaces" is not necessarily true in all cases and someone might run into it out of context. that is- here the "you" is specific to the poster and not necessarily anyone reading this post. just thought it worth pointing out.
    – Abel
    Jun 28, 2021 at 12:39

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