This is not a question but an observation:
As soon as I turned on Advanced Security I lost WiFi connection on my iPhone 11. As soon as I turned it off my iPhone 11 was able to get WiFi connection again. I have the latest version of IOS installed 13.3.1.
We've seen many many posts about this here lately ! Just keep it disabled and do not use it for now, it's buggy.;
Doesn't seem to affect my iPhone 11 Pro Max.
Do you have other security apps like Norton Internet Security or a DNS redirection service like Cloudflare (22.214.171.124) active on your iPhone?