Start by making sure that the Mac you're connecting to and the Mac you're connecting from are both using OS X Lion v10.7.5 or later. If the information in this article doesn't help you to resolve the issue, refer to the general steps for resolving issues with Back to My Mac.
Back to My Mac isn't available with macOS Mojave. If you use macOS Mojave, learn what alternatives you can use for file access, screen sharing, and remote desktop access.
“Back to My Mac... No Network.”
“Back to My Mac isn't working properly because the server isn't responding.”
Your computer can't connect to the iCloud service.
- Deselect the Back to My Mac checkbox in iCloud preferences, wait 15 seconds, then select it again to turn Back to My Mac back on.
- Check the System Status page to make sure that there are no issues listed for Back to My Mac.
- Determine whether your Internet Service Provider (ISP) is experiencing a service outage.
- Make sure that the TCP or UDP ports used by Back to My Mac are open on your firewall. Contact your ISP if you need help confirming that these ports are open. If you're in a corporate network environment or other organization where your Internet connection is managed for you, contact your network administrator to make sure that these ports aren't blocked.
“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.”
The NAT-PMP or UPnP protocol is turned off on your router or isn't supported by your router.
- If you're using an AirPort Base Station, use AirPort Utility to set NAT options for your base station.
- If you're not using an Apple router, refer to the instructions that came with your router to determine whether NAT-PMP or UPnP is supported and learn how to turn on either protocol. Some routers that advertise UPnP compatibility may require a firmware update from the manufacturer.
- If you don't have access to your router, contact your network administrator for help.
“Back to My Mac may be slow because NAT Port Mapping (NAT-PMP) is turned off on your base station.”
NAT-PMP is turned off on your AirPort Base Station. Click the Enable NAT Port Mapping button in the message, then use AirPort Utility to set NAT options for your base station.
“Back to My Mac may be slow because more than one device on your network is providing network services.”
Your computer is part of a multiple-NAT network, which means that at least one router (wireless or wired) is connected to another router, and each router is providing Network Address Translation (NAT). Follow the instructions for resolving a multiple-NAT configuration.