iCloud: What do Back to My Mac status messages mean?
Products Affected
iCloud
Symptoms
With OS X Lion v10.7.3 or later, the Back to My Mac section of iCloud System Preferences includes status messages if you are unable to connect successfully, or if there are performance issues with Back to My Mac.
Resolution
Status messages help diagnose issues that may occur when using Back to My Mac. See the sections below for specific status messages on performance and connection issues and how to resolve them.
Note: For the best user experience with Back to My Mac, update your Mac to OS X Lion v10.7.4 or later.
Status Messages
Service Enabled
If you are able to successfully turn on the Back to My Mac service with your iCloud account, you will simply see a checkmark next to Back to My Mac.
Performance Messages
Network configuration issues and router or modem device restrictions may cause Back to My Mac to be less responsive. Back to My Mac will continue working, but may perform more slowly, or may not work as expected. The Finder sidebar may respond slowly, or not at all, to enabling or disabling Back to My Mac on remote devices, or rebooting, or shutting down remote devices.
The following three conditions affect Back to My Mac performance:
1. NAT-PMP or UPnP is not enabled
This alert may appear in iCloud preferences:
"Back to My Mac may be slow because NAT Port Mapping (NAT-PMP) or Universal Plug and Play (UPnP) is turned off on your router."
This can happen if your Internet router does not support either the NAT-PMP or UPnP connection protocols. You may also see this message if your router device supports NAT-PMP or UPnP, but it is not currently enabled.
Resolution: Enable UPnP or NAT-PMP following the instructions or software included with your router. To learn about AirPort models that support NAT-PMP and how to turn it on if necessary, see Mac OS X: Back to My Mac requires AirPort base station or UPnP-capable third-party router. If you do not have direct access to your Internet router (for example, if you work in a company that has a large network that you do not administer yourself), check with your network administrator.
Note: Some third-party router devices that advertise UPnP compatibility may require a firmware update from the manufacturer.
2. Double NAT configurations
This alert may appear in iCloud preferences:
"Back to My Mac may be slow because more than one device on your network is providing network services."
This message appears when a double NAT configuration exists within your local network devices. This occurs when at least one router (wireless or wired) is connected to another router, and each is providing NAT.
Resolution: See Back to My Mac: "Double NAT" configurations may prevent Back to My Mac connections. You can read more about Network Address Translation (NAT).
3. NAT-PMP is not enabled on your Apple AirPort Base Station or Time Capsule
This alert may appear in iCloud preferences:
"Back to My Mac may be slow because NAT Port Mapping Protocol (NAT-PMP) is turned off on your base station."
This may happen if your Apple AirPort Base Station or Time Capsule is providing NAT, but NAT-PMP has been disabled on that device. See this article for more information about setting up and using Back to My Mac with an 802.11n-based AirPort base station or Time Capsule.
Note: If the issue persists with an AirPort Extreme 802.11n (2nd Generation),and you have enabled NAT-PMP using the AirPort Utility, update your base station firmware.
Service Not Successfully Enabled
Back to My Mac requires a valid Internet connection (see this article for assistance if you're using OS X Lion or this article for OS X Mountain Lion). If you are not connected to the Internet, this message appears:
"Back to My Mac... No network."
Resolution: Click the Network Diagnostics button to help troubleshoot your Internet connection. (For help with Network Diagnostics, see this article if you're using OS X Lion or this article for OS X Mountain Lion.)
Note: You may also receive this message if your Internet Service Provider (or ISP) is experiencing a service outage.
iCloud cannot be reached
If the iCloud service cannot be reached, you may see this message:
"Back to My Mac isn't working properly because the server isn't responding."
Resolution: Turn Back to My Mac off by selecting Back to My Mac, waiting 15 seconds, and then deselecting Back to My Mac.
Notes:
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You might also encounter this issue if outbound TCP connections to port 443 are blocked by a firewall. If you are in a corporate network environment, or large institution, where the Internet is managed for you, you may need to consult your network administrator if you observe this message.
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You may also observe this message if your Internet Service Provider (or ISP) is experiencing a service outage, or using a different connection protocol than you have configured in Network preferences.
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