@szewciulek 

Hi,

The "IoT network" feature allows you to setup a separate SSID with a separate password and separate security (e.g. if you wanted to make your main network WPA3-only, but some devices don't support WPA3). That's all.

If you want to isolate certain devices, then use the "Device Isolation" feature under "Advanced" -> "Security".
 

  @woozle Will devices in a standard network still be able to communicate with each other and those in the IoT network be separated from them?

  @szewciulek 

If you use device isolation, the isolated devices can communicate with each other.  The devices that are not isolated can also communicate with other devices that are not isolated.  It does not matter whether the devices are connected to the main network or the IoT network, i.e. isolated devices are grouped together and the non-isolated devices are grouped together.