fix(vpc): add first troubleshooting

Author: RoRoJ

pages/ipam/troubleshooting/conflicting-private-ips.mdx

@@ -0,0 +1,38 @@
+---
+title: Two different resources in my VPC have the same private IP address
+description: Resolve IP address conflicts in your VPC when two resources have the same private IP. Learn how overlapping Private Network subnets cause this issue and how to fix it by creating a new Private Network with a non-overlapping CIDR block.
+tags: ipam conflict same internal-ip private-ip
+dates:
+  validation: 2025-11-06
+  posted: 2025-11-06
+---
+
+
+You may find that two or more resources in your VPC have the same private IP address. This causes issues with network communication, as IP address conflicts can lead to intermittent connectivity, data routing errors, and service disruptions.
+
+## Cause
+
+This can happen if you have created two Private Networks with overlapping subnets in the same VPC.    
+
+DHCP assigns resources' private IP addresses from the CIDR block that was [defined for the Private Network](/vpc/how-to/create-private-network/#how-to-configure-cidr) when you created it. If two different Private Networks have overlapping CIDR blocks, the DHCP service may allocate the same IP address to one resource on Private Network A, and another resource on Private Network B.
+
+<Message type="tip">
+You can check each Private Network's CIDR block on its **Overview** tab in the Scaleway console. Then, use a tool such as [https://cidrclash.com/](https://cidrclash.com/) to check if the CIDR blocks associated with the other Private Networks in that VPC overlap or not.
+</Message>
+
+## Solution
+
+The CIDR block for a Private Network cannot be modified after creation of the Private Network.
+
+The solution when two Private Networks have overlapping CIDR blocks is to:
+
+1. Detach all resources from one of the Private Networks with a CIDR block that overlaps another in the VPC.
+2. Create a new Private Network in the VPC, with a new, non-overlapping CIDR block. 
+
+    <Message type="tip">
+    We recommend that you let Scaleway [automatically generate](/vpc/how-to/create-private-network/#automatically-generating-a-cidr-block) a CIDR block for the Private Network. This will be a `/22` subnet, guaranteed to be unique within the VPC, that will not overlap with any of your other Private Networks. It gives 1024 private IPv4 addresses, of which 1020 are available to be allocated to resources attached to the Private Network.
+    </Message>
+
+3. Attach the required resources to the new Private Network, where they will automatically be assigned new private IP addresses on the network by DHCP.
+
+Resources in the VPC should now all have unique private IP addresses. Traffic should be routed successfuly.

pages/ipam/troubleshooting/index.mdx

@@ -38,5 +38,6 @@ productIcon: IpamProductIcon
 ## IPAM troubleshooting pages
 
 <LinksList>
-  - [I can't delete my Private Network due to a reserved IPAM IP](/ipam/troubleshooting/cant-delete-pn-reserved-ip)
+  - [I can't delete my Private Network due to a reserved IPAM IP](/ipam/troubleshooting/cant-delete-pn-reserved-ip/)
+  - [Two different resources in my VPC have the same private IP address](/ipam/troubleshooting/conflicting-private-ips/)
 </LinksList>