How can I fix an iPad 2 not connecting to Wi-Fi after resetting network settings?

See this article.

If your iPhone or iPad won't connect to a Wi-Fi network - Apple Support

Bear in mind the second generation iPad was released by Apple fourteen years ago. This iPad is considered obsolete by Apple.

Start with basic WiFi troubleshooting - as detailed here:

If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support

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

Consider that your Router, to which you are attempting to connect, may be configured to require support for security features that are not supported by older versions of iOS. If you have an older iPad and your router is configured for WPA3 or WPA3/WPA2 mixed authentication, you will need to change this to WPA2 PSK(AES). Newer models of iPad support WPA3.

Some Mesh WiFi Routers are known to be troublesome in some circumstances.