Why does my Bluetooth device show up in the list but fail to connect?

Because it is no longer in pairing mode. A Bluetooth accessory advertises itself so it can be found for a short window, then goes back to being visible only to devices it already trusts. The name stays on your phone's list because that entry is a record of a past pairing, not proof that the accessory is listening. Put the accessory back into pairing mode — usually a long press until a light flashes — and connect within that window.

I deleted the device on my iPhone. Why does pairing still fail?

Because the pairing record is stored at both ends. Deleting it on the phone removes your half; the accessory still believes it holds a valid key for a device it thinks it knows, and the handshake fails on that mismatch. Always clear the pairing on both sides, then pair again. If the accessory has no way to delete a pairing, its factory reset does the same job.

Does turning Bluetooth off and on help?

Sometimes, and it is worth one try because it is instant. Toggling Bluetooth rebuilds the phone's own Bluetooth service state, which can clear a stuck scan. What it cannot do is change the key stored on the accessory, so if the fault is a mismatched record, the toggle will appear to work and then fail again at the same point. Use it as a cheap test, not as the fix.

How many Bluetooth devices can an iPhone have paired at once?

There is no published limit from Apple on stored pairings, and in practice a long list is not itself a fault. What matters is that only a small number are active at a time, and audio accessories connect to one host at a time.

Bluetooth Won't Pair or Won't Find the Device? Work Through This

Short answer: "It does not appear in the list" and "it appears but will not pair" are two different faults with two different fixes. The first is almost always that the accessory is not advertising itself. The second is almost always a pairing record that only one side has deleted.

Which of the two you have

What you see	What it usually means	First move
The device is not in the list at all, even after waiting	The accessory is not in pairing mode, or it is out of range, or it is not powered	Put the accessory into pairing mode and keep it within a metre of the phone
The device is listed, you tap it, nothing happens	One end holds a stale key from an earlier pairing	Delete it on both ends, then pair again
The device connects for a few seconds, then drops every time	Half-established record — often a device paired to something else in between	Delete on both ends; check nothing else is holding it
It paired before and now asks for a code you do not have	The record is gone on the accessory side after a reset	Use the accessory's own default passcode, or re-pair from its instructions

The distinction matters because the fix that everyone reaches for first — turning Bluetooth off and on — only addresses the first row, and only sometimes.

Why the name stays in the list after the device is gone

The Bluetooth list on your phone is a list of records, not a list of live devices. When you pair, the two devices exchange a shared key and each stores it. From then on the accessory stops advertising itself to strangers and answers only devices that can prove they hold that key.

That design is why an old device can sit in the list for months while switched off, and why a device that is sitting right next to you can be genuinely absent from a scan: it is not hiding, it has simply finished advertising. Pairing is not a state that persists; pairing mode is a temporary window, usually a minute or two.

So the first thing to establish is not a setting, it is a physical fact: is the accessory currently in pairing mode? Most headphones and speakers tell you with a light — a fast double blink or a colour change means pairing mode, a slow single blink usually means "reconnecting to something I already know". If you cannot get the light to change, you are not looking at a phone problem.

The two-ends rule

This is the most common reason a re-pair fails, and it is invisible from the phone.

A pairing record is stored at both ends. When you tap *Forget This Device* on the iPhone, you delete your half. The accessory still holds its half — a key for a device it believes it knows. Pairing then starts from an inconsistent state: the phone offers a fresh pairing request, the accessory tries to resume a relationship it thinks still exists, and the handshake ends in a connection that either fails or half-works.

The order that avoids it:

On the iPhone: Settings → Bluetooth → tap the ⓘ next to the device → *Forget This Device*.
On the accessory: do the equivalent. For most headphones and speakers that is a long press (often 10–20 seconds) on the power or pairing button until the light behaves differently; some have an explicit "clear pairing list" in a companion app.
If the accessory has no such control, its factory reset clears every stored key. That is heavier, and it will also drop the accessory from any other phone, tablet or car it was paired to.
Then pair: put the accessory in pairing mode first, keep it near the phone, and complete the pairing.

If a clean two-ended re-pair gives you a stable connection, the record was the problem. If it still fails at exactly the same point, the fault is not in the record — check whether another device already holds the accessory, and check the accessory's own firmware.

Things that look like pairing failures but are not

Another device got there first. Audio accessories connect to one host at a time. If an iPad, a Mac or a second phone nearby is holding the link, the accessory will refuse yours — and because it is connected to something, it is also not advertising.
Too many active devices. An office or a train carriage full of Bluetooth is a hostile place for a single link. Pairing may succeed and the connection still be unusable.
A USB 3 cable or drive right next to the phone. USB 3 radiates in the same 2.4GHz band Bluetooth uses. Move it a foot away and retry before concluding anything about the phone.
A device that needs a passcode. Some keyboards and car kits want a code — commonly 0000 or 1234, but check the accessory's own instructions rather than guessing. A pairing that fails at the code prompt is not a radio fault at all.
Low battery on the accessory. Some accessories advertise weakly, or stop advertising entirely, when their battery is nearly flat. Charge it before you debug it.

When it is worth suspecting the phone

Faulty phone-side Bluetooth is rare, and it has a recognisable signature: every accessory fails to pair, including ones that worked yesterday, and the Bluetooth toggle is greyed out or the list will not populate at all.

In that case, in this order:

Restart the iPhone once. This restarts the Bluetooth service without touching any pairing record.
Check Settings → Bluetooth is not being restricted — under Screen Time content restrictions, and via any configuration profile or MDM policy on a managed device.
Only then consider Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings. It clears every saved Wi-Fi password and every Bluetooth pairing, so it is the last step, not the first.

If a device pairs with another phone but never with yours, and every device behaves that way, that is the point at which a hardware check is reasonable.