iPhone Screen Mirroring: Device caching and discovery

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Level 1

5 points

iPhone Screen Mirroring: Device caching and discovery

iPhone 13 mini running iOS 26.2

I went to mirror a stream to a previously used Roku device. It popped right up on the Screen Mirror list, but would not respond. Investigation of the Roku showed it had lost its network connection - so what showed on the Screen Mirror list was still in cache, not from a current request - and sure enough, after repairing the Roku's LAN connection, it worked fine. That raised a number of questions for which I realized I need answers:

Does the iOS device (iPhone) cache a Screen Mirror list for each network?
How does the iOS device build its list of Screen Mirror servers on a local network? I presume it broadcasts a request to the LAN, the first time it is invoked on a new LAN, asking "Does anyone provide this service?" - Is that correct? [Is that broadcast a Bonjour function?] If not, how does it acquire its list of Screen Mirror servers?
To avoid the problem of false positives in the Screen Mirror list, how can I clear that cache (#1) and issue a new request (#2) for current Screen Mirror servers? How can iOS avoid showing servers that no longer exist on the network?
Is there any limit to the number of networks cached by iOS, or the number of servers cached per network?

More generally, is there a good resource to read how iOS manages this issue?

iPhone 13 mini

Posted on Feb 1, 2026 5:19 AM

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Answer 1

Jeff Donald

Level 8

45,660 points

Feb 1, 2026 5:39 AM in response to JohnKaufmann

Apple and Apple Support do not participate in these communities. The information, if not publicly available in the device specifications (which it’s not) is generally unavailable.

You're welcome to contact Apple Support and they might provide some limited information. You might also want to participate in the Apple Developer’s Forum. These communities are oriented towards consumer troubleshooting issues.

Apple Developer Forums

If you’re in the US, please call 1-800-MY-APPLE, or outside the US, consult the support articles below. In Canada, call 1-800-263-3394.

Contact Apple for support and service - Apple Support

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Answer 2

JohnKaufmann Author

Level 1

5 points

Feb 1, 2026 1:59 PM in response to Jeff Donald

Thanks for your reply. I contacted Apple Support yesterday, was advised to go to Genius Bar at the local Apple Store, which I did. Kira advised me to put the question here, so did that next.

Questions like how to avoid false positives in a server list, and how to clear the server cache, seem like consumer troubleshooting issues, but I agree that the other questions, like:

- Is a server list cached for each network?
- What is the limit to number of networks cached, or number of servers per network?
- What protocol is used to assemble the server list?

seem to go beyond consumer troubleshooting (sometimes these questions inevitably overlap), so I appreciate you pointing me to the Apple Developer Forums.

May I ask an unrelated question: How did you put a space in your name/handle? (It seems to be a regular ASCII 20h space, which the forum system would not let me include.) Is the answer as simple as "spaces were allowed, but no longer"?

Thanks again for your pointers.

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Answer 3

Jeff Donald

Level 8

45,660 points

Feb 1, 2026 3:01 PM in response to JohnKaufmann

You’re welcome. Well let’s cross our fingers and hope someone with the specific knowledge required to answer your questions sees your post. I’m a former Apple Store manager and I can say with confidence that no one ever asked those questions, at least to my knowledge. The underlying issue is Apple doesn’t publish much of this type data for iOS, unless you’re a developer, and then you’d have a need to know.

Consumers want their iPhones to just work. They only rarely want a why, just how do I fix it. In the case of your issue, it becomes Apple screwed up my Roku, fix it now or I’m buying a Samsung. Very few people ask about the whys and wherefores. Just make it work.

In regard to my name, I signed up over 25 years ago and it just worked. To the best of my knowledge it still works that way. However, I see your username lacks a space, so I guess not. If you would like a space, I can ask a moderator if they can edit your username.

I hope you have a great rest of your weekend.

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Answer 4

JohnKaufmann Author

Level 1

5 points

Feb 1, 2026 10:27 PM in response to Jeff Donald

Thanks so much. The name is OK - I had wanted it to just be normal, but it's clear enough, and doesn't really bother me - certainly not enough to ask anyone to fix it.

Bonne semaine, as my French daughter would say.

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