@Solla-topee 

Hi Solla-topee,

Thank you for your response. Here are my answers to your questions:

1. The Powerline Frequency setting is set to AUTO.
2. I observed the frame rate drop to 25fps on the Video & Display>Frame Rate page. Initially, I set it to 30fps, but after a while, the 30fps option disappears and it defaults to 25fps. This drop is also noticeable when streaming via RTSP, where there is a brief timestamp flicker indicating the FPS drop.
3. Changing some settings, such as resolution, sometimes makes the 30fps option reappear, but it still defaults to 25fps. I have to manually adjust it back to 30fps, but after a period of time, it drops back to 25fps again.
4. After multiple tests, I found that setting the Powerline Frequency to 60Hz prevents the FPS drop issue. It seems that the automatic power frequency detection might be faulty, incorrectly detecting 50Hz and causing the drop.

I hope this information helps in diagnosing the problem. I believe a firmware update could address this issue.

Best regards

  @FishYes I'm also searching on the same topic (because my C225 camera also drops from 30 to 25 fps) and saw that on another thread Solla-topee said this:

"Hi,
The max FPS option is related to the Powerline Frequency settings(On the camera's Device Settings>Advanced Settings page). If you select 60Hz on the Powerline Frequency page, you can see the 30fps option on the camera's Device Settings>Video & Display>Frame Rate page. 
It's suggested to select the Powerline Frequency option according to your region's standard."

I wonder why the max FPS is tied to Powerline Frequency? In my country the power is 50Hz, so now I know why it drops to 25 FPS. But why can't I have 30 FPS despite power being 50Hz?

  @JCWC 

Hi JCWC,

Thanks for your question. The issue with the FPS being tied to the Powerline Frequency settings is indeed puzzling. Here's what I've gathered:

The Powerline Frequency setting (50Hz or 60Hz) is related to the electrical grid frequency in different regions. Many cameras, including the Tapo C125 and C225, use the power frequency to reduce flickering caused by artificial lighting. In regions with 50Hz power, the camera might default to 25fps to synchronize with the power frequency and minimize flicker. Similarly, in 60Hz regions, it defaults to 30fps.

According to the official explanation, this design is intended to synchronize with the power frequency to reduce flickering issues. However, I personally suspect that the auto-detection feature might not be entirely accurate in some cases, causing it to misjudge the power frequency and consequently limit the frame rate.

I hope this clarifies the issue. It would be great if TP-Link could offer a firmware update allowing users to override this setting, so we can choose 30fps regardless of the power frequency.

Best regards