iPhone not showing 5G WiFi

Hello everyone, I use iPhone 14 Pro Max running iOS 16.2. The problem is my iPhone does not show 5G WiFi Networks. I investigated the problem and I found that whenever I restart my iPhone it shows and connects to 5G networks but after a few minutes the it disconnects and never show the 5G WiFi again until I restart my iPhone. I checked on different devices i.e. TV, android phone, and laptop, the same 5G WiFi works fine with other devices. then I checked on different iPhones and the findings were strange, any iPhone above iPhone 11 for example 12, 13, and 14 has this issue, and the iPhone 8 and iPhone 11 work just fine with the same 5G WiFi network. I have tried resetting the network settings of my iPhone, after the reset, the iPhone restarts and detects and connects to the 5G WiFi but after some time it disconnects and don't show the 5G WiFi network.

The WiFi router I am using is MI Router 4A.