My iPhone tells me that my wifi network has low security

Note that to eliminate the warning if you are using WPA2 it needs to be WPA2 Personal AES. The AES option may be in a different field on the same page as the WPA2 setting.

To eliminate the weak security warning, change the security settings on your router to WPA3 Personal, WPA2/WPA3 Transitional or to WPA2 Personal AES. How you do that varies by router. If you don't have the instructions for your router, do an internet search for instructions for your router brand/model or if your router is supplied by your internet service provider, check their website or customer support. Also see: Recommended settings for Wi-Fi routers and access points - Apple Support

matiastideida wrote:

The problem precisely is that my router is configured in WPA2 Personal and has an AES key. It does not allow me to have another key that is not AES, but it does have WPA2, as I show in the attached screenshot.

https://discussions.apple.com/content/attachment/dfb5cf50-648f-4b44-bd65-c9d7b7b828cc

That should work but I don't know why it isn't.

Try entering the wifi settings on your iphone and select “forget this network”, then re-enter the password and re-connect. (After ensuring your router is set to use WPA2(AES) or WPA3)