Setting up network security what is iPads domain name?

Debfreie wrote:

Trying to secure my router network security, it says open network.

Open Network indicates that your WiFi network is not configured for WPA security - and has no encryption; anyone can join the network without providing a Password.

To rectify this you will need to access your WiFi Router’s management webpage from a browser - and configure your WiFi Network to use WPA3 security - or if not supported, WPA2. You’ll need to set a WiFi network password.

Recommended settings for Wi-Fi routers and access points - Apple Support

If you don’t know how to configure your WiFi Router, refer to its setup manual. If the Router was provided by your Internet Service Provider, their technical support pages will provide guidance for accessing and setting-up the router.

“Domains” can have many meanings - but in general computing parlance the term is very often synonymous with Microsoft computers - as opposed to iOS/iPadOS devices.

Perhaps this description will help you to understand and refine your question with appropriate context:

https://www.techopedia.com/definition/1326/domain-networking

Not much information here with which to base guidance. Where are you attempting to enter domain information - your router, or someplace else?

Unless you have a specific need, perhaps leave the field blank until you have more information.

Debfreie wrote:

Trying to secure my router network security, it says open network.

That has nothing to do with your iPad. You need to login to the routers admin page and setup security for your WiFi network directly on the router itself. Do a web search for the setup guide for your make and model of router and follow the instructions from the manufacturer about how to setup WiFi login security on your router.