iPhone 13 Wi-Fi Connection Slows to a Crawl Despite Fast Internet

I purchased an iPhone 13 from Troy Apple on 25.11.2024, just three days ago. While every other device in my home connects to Wi-Fi with excellent speed, the iPhone 13 experiences extreme slowness when connected to the same network. I have tested the Wi-Fi with multiple devices, and all function normally, but the iPhone 13 struggles even to load a simple video.

I ensured that backups and other data-heavy processes were turned off, yet the issue persists. Interestingly, the phone works perfectly fine when connected to mobile data, so this is clearly a Wi-Fi-specific issue. I need this problem resolved promptly, as this is not the performance I expected from a premium device. Please provide a solution immediately.