What causes an IP conflict?

When i try to setup my ewons wan it fails. I see ecfg-LAN and WAN IP addresses configured are conflicting in the event logs.

If you are seeing an issue in your event logs that say “ecfg-LAN and WAN IP addresses configured are conflicting” This means the Ewon LAN network has an IP assigned in the same subnet that the WAN network is being configured for. This document is intended to cover details on IP addresses and why the Ewon needs two subnets along with workarounds.


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  1. Overview of networks IP addresses and routing
    1. Calculate subnet from IP and mask
    2. Routing and how they overlap
  2. The Error
    1. Symptoms in the Ewon and error messages
  3. Reasons.
    1. Matching subnet
    2. DHCP trying to assign address in same range.
    3. Incorrect mask
    4. Overlapping subnets
  4. Solution
    1. Change one of the networks
    2. VLANS
    3. Router or another Ewon as a gateway

1. Overview of networking IP address and routing

Before we get into the issues on the Ewon It is good to have a basic grasp of IP addresses and how they are used with routing.
An IP address along with a Subnet Mask is what an Ethernet device uses to route traffic, telling the Ewon what network it can reach though its adapters. To do this it first calculates the subnet that it is connected to. The subnet is determined by a combination of the IP address and the subnet mask.

To calculate the subnet, as the name applies, the subnet mask is applied to the IP address. Each octet of the IP is ANDed with the corresponding MASK octet. The result is the Network Subnet. Typically, the mask octets are only 255’s making the process easy with masks like or but you can also have something like This is outside the scope of this doc, but worth being aware of. Here is a quick example and breakdown. Using IP with a subnet mask of or in CIDR (Classless Inter Domain Routing) notation written as

Using the /24 format is just stating the number of bits and saving time from writing out the full mask. Where has 24 bits /24 is used. has 16 and /16 is used. or 1100 0000.1010 1000.0000 0010.0000 0110
& or 1111 1111.1111 1111.1111 1111.0000 0000 (24 bits) 
↓↓↓  ↓↓↓ ↓↓↓  X     ↓↓↓↓ ↓↓↓↓   ↓↓↓↓ ↓↓↓↓  ↓↓↓↓  ↓↓↓↓  xxxx  xxxx or 1100 0000.1010 1000.0000 0010.0000 0000

If a device is connected to two networks, it looks at the networks to decide where to send the message. As an example, if a device has one adapter connected to and a second on and it has a message for It will see the first adapters has access to 192.168.0.x matching the message destination and it knows to send the traffic out that port.

What would happen if a PC had two adapters, one network adapter with and a second of Both adapters are in the same subnet so the device might send a piece of the message out one adapter and then another out the other. To avoid this most device, prevent two network adapters from connecting to the same subnet.

There is another more complicated issue, where a smaller mask is used creating a bigger network. This means that a subnetwork can be a subset of another. Here is an example: The Ewon LAN is set the ( calculating the subnetwork like above we see the subnetwork is This means any device with an IP starting with 192.168 will be in the adapters network range. If the WAN adapter tries to set an IP of it will be a conflict.
For more tricky Subnet masks this site can be helpful. IP Subnet Calculator
Other reading: Understanding IP Addressing and CIDR Charts — RIPE Network Coordination Centre

2. The Error

Symptoms: The Ewons WAN will not connect, the Ewon will show no internet access and the Internet wizard will fail. Event Logs will indicate issues starting the WAN interface typically including an error on a LAN WAN conflict.

3. Reasons

If you have a LAN WAN conflict on the Ewon it means the two ethernet interfaces are trying to get an address in the same network. This in turn means one of the adapters will not be able to get an address. Since the LAN is typically static it will keep its IP address and the WAN side will not get an address.
This issue has a few common reasons

  1. The Ewon’s WAN and LAN are the same physical network. This means both the LAN and WAN would each need an IP in the same subnet.
  2. The networks are separate but use the same subnet. This is common for a networks. The WAN will try to grab an IP address using DHCP but will fail to apply it when the conflict is detected.
  3. Subnet mask makes the subnet range too large. If the Ewon LAN uses it will route all networks that start with 192 so even if the WAN is the Ewon LAN will see the falls within.

4. Resolution or work arounds

The recommended solution for an IP conflict is to change one of the network subnets the Ewon is connected to.

  1. Update the LAN device to use a different subnet and set the Ewons LAN to match.
  2. Use a VLAN on the WAN to move the device into a separate network. Often Ewons are installed with the WAN connected to a Managed network that has advanced managed switches that can set up additional networks through one network switch. The managed switch can be configured to connect the Ewon to another subnet. You will need to work with the local IT team to check if this is a possibility.
  3. This method is not strongly recommended but can be used as a workaround. Add a second Ewon or router as a gateway where the LAN is used for the WAN of the Ewon you are setting up. This method sets up a secondary network that routes traffic from the LAN into the WAN which would be the same network.

Here is a PDF of this to save it for future reference.
You are seeing an error for an Ewon LAN WAN conflict.pdf (223.1 KB)