iPhone 12 Pro Slow Wifi Connection Problem

Hello all,

I am experiencing a slow wifi connection problem with my iPhone 12 Pro (iOS 14.3).

I test the connection speed using an app called "Speedtest" and it shows 70 Mbps download speed. After rebooting and testing again, it jumps to 250 Mbps download speed (my current contract limit).

I am experiencing this problem time to time since the first release of the phone (with previous iOS versions) and I fix it every time by rebooting it while any other setting remains unchanged.

I tried to fix it by changing the low power mode, location services, mobile data and flight mode but only rebooting seems to work.

I know it is not related to the environment or the wifi router because when my iPhone shows 70 Mbps, my iPhone 6s shows 250 Mbps (not tested at the same time but one after another).

Does anyone have a clue why this might be happening?

Before reboot:

After reboot:

Thanks,