@Dayi7789 

Hi,
1. Usually, you can control your Tapo camera locally and remotely after configuring it successfully on the Tapo app, and no additional settings need to be configured to control the camera remotely.

2. If you want to stream the camera remotely via the RTSP/ONVIF protocol rather than use the Tapo app, it's required to open port 554/2020 on your router for the camera, and then RTSP access URL is rtsp://the public IP address on your router:554/stream1 or rtsp://the public IP address on your router:554/stream2.

3. The DDNS is a feature on the wireless router rather than the camera.

Best Regards

  @Dayi7789 

Hi,
You can refer to the instructions below to troubleshoot if you fail to control the camera remotely.
What to do if I can't control my Tapo cameras on the Tapo app?
 

Please help confirm the following information if the problem remains:
1) The LED status on your camera.
2) Send me(@Solla-topee) the MAC address of your camera.
3) Your network diagram, such as ISP—wireless router ))) ((( Tapo C200, and the model number of your wireless router.

Best Regards

  @Dayi7789 

Hi,
If three of your cameras are working and only one camera can't be controlled remotely, you can try:
    1. Reboot the camera and check if it helps.
    2. Check if your router has configured MAC Filtering, ACL, or Firewall rules that may block the camera from connecting to the internet. If so, disable/remove these rules for a try.
    3. Try to factory reset the camera and reconfigure it via the Tapo app.
Best Regards

  @Dayi7789 

Hi,
Take one of your cameras as an example, you can try the following steps and test if you can control it remotely.
1. Hold the reset button on a camera for 10 seconds to reset it, and wait for the LED to turn to flashing red and green.
2. Enable a hotspot Wi-Fi on your phone, use a different phone to configure the camera via the Tapo app, and connect it to the hotspot Wi-Fi.
3. Once the camera is configured successfully, check if you can control it remotely via the mobile data.
Best Regards