I suspect your wifi is working, it only the “connectivity check” that is failing. At least if you can try to use the internet while on wifi only (mobile data disabled) I hope this is what you find.
The problem most are facing is that if you use Cloudflare as your DNS provider, then it is failing to resolve captiveportal.kuketz.de which is the site we use for connectivity checks. Changing to “Quad9” resolved it for me (9.9.9.9). Please see this discussion: