AirPods not showing on Find My Iphone

They might be offline:

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If you didn't turn on Find My [device] before your AirPods went missing, you can't use it to locate your device. If you see "No location found" under your AirPods, you can't play a sound to find them but you might be able to get directions to the location where they were last connected. If your AirPods do come back online, you'll get a notification on the iPhone, iPad, or iPod touch you use them with.

Find My is the only way that you can track or locate a lost or missing device. There is no other Apple service that can find, track, or otherwise flag your device for you.

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copied from: How to find your lost AirPods - Apple Support

In another article about "Find my" Apple mentions, that if more than 24 hours passed since the last location was sent to Apple, locating the device can only be done, if the device connects to a network again.

If Find My iPhone is offline or not working - Apple Support

Did you already check this article about locating your AirPods?

How to find your lost AirPods - Apple Support

You're welcome 🙂