Diagnosis
This is almost always a WiFi issue, not a problem with the projector's processing. The screen mirroring function (Miracast/AirPlay) requires a very strong and stable 2.4GHz WiFi signal between your phone and the projector.
How to Fix It
1) Improve the WiFi environment. Make sure both your phone and the projector are as close to your WiFi router as possible. 2) On your phone, before mirroring, go to WiFi settings and forget any 5GHz networks, forcing it to connect to the 2.4GHz band. 3) Reduce interference. Turn off other WiFi devices in the room temporarily, especially other streaming devices.
If That Didn't Work
For a much smoother experience, use a wired connection. Get a USB-to-HDMI adapter for your phone (like a Lightning to HDMI or USB-C to HDMI) and plug directly into the projector's HDMI port. This bypasses WiFi completely.
Heads Up
Even under perfect conditions, the mirroring function on this model can have noticeable latency (lag). It's fine for movies, but it'll be frustrating for gaming or anything requiring real-time response.