On a typical Wi-Fi network, when multiple devices connected to the same Wi-Fi network connects to the internet, from the internet side, it will show that they all have the same IP address.
In other words, devices connected to the same Wi-Fi network will have the same public IP address.
You can test this.
When you connect to the internet through, for example, your home Wi-Fi with your phone and PC and you run “what is my IP address” from both devices, the returned results will give you the same IP address for both.
How is this possible?
You may have heard that no two devices can ever have the same IP address. This is true but there are several factors to consider on a Wi-Fi network.
How are IP addresses allocated?
Your public IP address is allocated by the internet service provider. This is the IP address that is visible from outside the Wi-Fi network.
If you are using your mobile data on the other hand, your IP address will be assigned by your mobile data service provider. Once you connect to Wi-Fi, your IP address will change to one allocated to the Wi-Fi router by its internet service provider.
How are IP addresses allocated on a Wi-Fi network?
Multiple devices can connect to a Wi-Fi router. The Wi-Fi router makes a single connection to the internet, through which the devices on the wi-fi network connects to the internet.
The IP addresses works pretty much the same.
Inside the Wi-Fi network, the router allocates local IP addresses (Private IP) which allows the router to identify the devices within its network. The local IP addresses are only visible within the Wi-Fi network and is unique to each connected device.
On the internet side of the router, it has one connection to the internet and therefor one IP address.
It is the router’s IP address that is visible from the internet side for all devices connecting to the internet through this router.
This means that your visible (Public) IP address will be based on the Wi-Fi router’s IP address and not on the local IP addresses of each device.
There are exceptions
We are talking about a typical wi-fi connection here.
An example of an exception is if one or more devices connected to the Wi-Fi network are using VPN. With VPN, the VPN IP address will be visible on the internet and not that of your Wi-Fi router. This is because with VPN, your connection will link directly to the VPN network and from there connect to the internet. Because in this case the VPN service is making the connection to the internet, it will be the IP address of your VPN service provider that will be visible on the internet and not that of your device, or your Wi-Fi router.
Another example is when multi-WAN routers are used. Multi-WAN routers can have more than one internet connection.