1. Which iPhone are you using?
2. What software version on the iPhone (Settings > General > About). If it’s lower than 15.4, update the phone through Settings > General > Software Update
3. What kind of cable are you using to plug into the Seltos? I’ve had problems with nearly all aftermarket cables and have opted for the more expensive Apple-brand cables which work flawlessly. Feel free to post a picture of your cable if you’re not sure and I can verify
4. Which USB port in the Seltos are you plugging it into?
5. Can you verify that CarPlay is enabled in the Seltos? (Press the SETUP physical button below the screen, tap on device connections, tap on Phone Projection Settings, tap on Apple CarPlay on the left side, and make sure the “Enable Apple CarPlay” checkbox is checked)
6. If all the above doesn’t work, talk to the dealer. They’re not usually good with troubleshooting CarPlay, but they can replace the head unit or USB ports under warranty