Could you try on a different internet connection just to remove any potential issue with your network?
Sone advice from @Kami_Nick on a different post (might help you):
Please check these settings on your phone, also try to uninstall the application then reinstall it. Please reset the camera before pairing it again on the mobile app.
Things to check on your mobile phone’s settings:
1.On your Wi-Fi Settings make sure that your phone is connected to a 2.4GHz network.
2.Location or GPS should be turned ON.
• IOS: Settings > Privacy > Location Service > Make sure that YI Home App is set to Always
• Android: Settings > Click on search and type location. Select App permission. Enable location. If you don’t see the location, tap Security & location. Enable location.
3.The Wi-Fi Password should not include any special characters.
To pair your camera, do the following:
1.Connect the camera with the USB cable and adapter, and plug the adapter into a power outlet. If the camera is battery operated, make sure the batteries are fully charged and inserted properly into the camera.
2.Open the app and log in to your account.
3.To add your camera, select the ‘+’ icon.
4.Under Select Device(s), choose the camera that is going to be paired with the app. If you aren’t sure, click on the QR code under Select Device(s). Scan the QR code on the bottom of the camera.
5.Under Set up the camera, Please wait 20 seconds until you hear, “Waiting to connect”. If you hear the voice prompt, click on I heard “Waiting to connect” at the bottom of the screen. If you don’t hear waiting to connect click on the link called, I did not hear it. Use a paper clip to push the reset button in for a 3-5 seconds. If you have a battery camera, hold down the operation button on top of the camera for 3-5 seconds to reset. Then select Reset successful.
6.Under Connect to Wi-Fi, first, make sure the Wi-Fi name is correct. Only the Kami Indoor camera can connect to the 5GHz Wi-Fi band. All other YI cameras use the 2.4GHz Wi-Fi band. Then enter your Wi-Fi password correctly. Select Connect to Wi-Fi.
7.Then face the QR code directly at the camera. If you hear “QR code scan is successful,” press next. If you did not hear anything, click on the link at the bottom of the screen.
8.The camera will go into retrieving pairing status that can take 1-2 minutes until the camera is successfully paired with the app.
9.Create a name for the camera. This can be a custom name or the location of the camera.
10.Then click “Confirm Activation” to activate the free cloud service. If your camera does not include a free cloud service, you can still purchase a cloud service by clicking on “Purchase Cloud Subscription” during the setup. If you don’t want to use a cloud subscription, click on Start using my YI.