Wifi „no internet connection“ issues (iOS16)

Ever since upgrading to iOS16 my two phones have serious Wifi issues. It connects to my home Wifi but the connection is sluggish and unstable and the connection receives the label „no internet connection“. I have multiple other devices including two iPads, an iPhone on iOS15, a MacBook, all of which have no issues at all. This issue has also been reported last year after iOS15 rollout here. The issue does not occur on both phones simultaneously and pretty much at random. It first appeared on my older iPhone 12 and after receiving my iPhone 14 Pro Max, which has been setup using an iCloud Backup from the 12, the problem appeared there as well immediately.

Apple Support hasn‘t been much help yet. Reset network settings, delete all VPNs, restart router, set proxy to automatic, etc… all didn‘t help. This issue is also a pain to communicate. One Apple Support guy declared the problem solved as I could load a website (yay!). So my hope is someone from the community has silently found a solution for this.