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Devices can’t see each other? Six checks.

Two devices only find each other when they share a network, have the app open on both sides, and nothing blocks the local network: the Local Network permission on iPhone or Mac, the Windows firewall, a VPN, or a Wi-Fi that keeps devices apart. Check in this order. If nothing works, your phone’s hotspot puts your devices on a network of your own in a minute.

Reviewed on 21 September 2026 by Fabien Chauveau, who makes GreySpace. These checks apply to other local transfer apps too.

Most common first.

After each check, tap “Détecter” (Detect) in GreySpace. The app also searches on its own every 20 seconds.

  1. Both on the same network

    The same Wi-Fi name on both devices. Common traps: the phone still on 4G or 5G, one device on the router’s guest network, the computer on a neighbour’s Wi-Fi or a badly set up extender. A computer plugged into the same router by cable counts as the same network.

  2. The app open on both

    A device is only visible while the app runs on it. On iPhone, iOS pauses the app as soon as it goes to the background or the screen locks: keep it open, on screen. GreySpace reminds you: “Keep GreySpace open to receive files.”

  3. iPhone and Mac: the Local Network permission

    The first time you open the app, your iPhone asks whether it may find devices on your local network. If you said no, it can’t see anyone, and GreySpace can’t tell you yet.

    • On iPhone: Settings, Privacy & Security, Local Network, then turn on GreySpace.
    • On Mac (macOS 15 or later): System Settings, Privacy & Security, Local Network, then turn on GreySpace.

  4. Windows PC: the firewall

    The typical sign: the PC sees the phone, but the phone can’t see the PC. Windows blocks what comes in to GreySpace, often because the app was only allowed on one kind of network, private or public. GreySpace then says the Windows firewall is probably blocking incoming access.

    • Open Windows Security, Firewall & network protection, then “Allow an app through firewall”.
    • Click “Change settings”, find GreySpace, tick Private and Public, then OK.

    At home, you can also set your Wi-Fi as a private network: Settings, Network & internet, Wi-Fi, Manage known networks, your network, Network profile type, Private. Only on a network you trust.

  5. VPN off while you transfer

    An active VPN can reroute all traffic, local network included, on the phone as on the computer. Turn it off while you transfer, or switch on its local network access option if it has one.

  6. A Wi-Fi that keeps devices apart

    A router’s guest network, hotel, school or office Wi-Fi: many stop devices from talking to each other, for safety. Each one has internet, none can see the others. GreySpace then says no device answers on the network (it says the same when the app isn’t open on the other side: check point 2 first). The fix: what works on these networks.

People often ask

For anything else, email us.

The PC sees my iPhone, but my iPhone can’t see the PC. Why?

It’s almost always the Windows firewall: the PC can reach out to the phone, but nothing can reach in. Allow GreySpace on private AND public networks in Windows Security, Firewall & network protection, “Allow an app through firewall”.

Do the devices need internet to see each other?

No. They need a shared network, not internet: a router whose internet is down works, and so does a phone’s hotspot. Files go from one device to the other without a server.

The other person doesn’t have the app. How do I send to them?

In GreySpace, show the QR code: it opens a page in the other device’s browser, which can receive your files or send you some, with nothing to install. Same rule: both devices on the same network.

I checked everything and still nothing.

Try your phone’s hotspot: it fixes a wrong network and an isolating Wi-Fi in one go. Otherwise, write to [email protected] with your two devices, your network and the message GreySpace shows: we’ll get back to you.

See also

Didn’t find your answer? Write to [email protected] or drop by Discord with your two devices, your network (home router, office, hotspot) and the message GreySpace shows.

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