If you experience one of these issues with Back to My Mac, your router settings might be the cause:
- The Mac that you try to connect to might appear in the Finder sidebar, but you can't connect to it.
- The Mac might not appear in the sidebar at all.
- An alert might say, "Back to My Mac may be slow because more than one device on your network is providing network services." Get help with alerts.
Follow these steps for help
- Open Network Utility. Here's how:
- OS X Mavericks or later: Go to /System/Library/CoreServices/Applications. Or click to open Spotlight and type Network Utility.
- OS X Mountain Lion or earlier: From the menu bar, choose Go > Utilities. Double-click Network Utility.
- Enter "icloud.com" in the Traceroute tab, then click Trace.
- Find the line that begins with the number 2 in the results. In that line, if you see an IP address in one of these ranges, your network has a multiple-NAT configuration* and you should finish the steps in this article:
If you see an IP address that isn't in one of these ranges, get help with other Back to My Mac issues.
- Make sure that you have OS X Lion v10.7.5 or later.
- If a software update doesn't fix the issue, you need to turn off NAT* on a network device. Here's how:
- If you don't use a router made by Apple, or if you use a modem as a router, check the equipment's manual to learn how to turn off NAT.
- If you use an AirPort Base Station, follow these steps to turn off NAT:
- Choose Go > Utilities from the menu bar, then open AirPort Utility.
- Select your base station and click Edit in the pop-up menu.
- Click the Network tab, then choose "Off (Bridge mode)" from the Router menu.
- Click Update to restart the base station.
- After the base station restarts, make sure that your Internet works.
* Sometimes, connected routers provide too many layers of Network Address Translation (NAT), which creates a multiple-NAT configuration that interferes with Back to My Mac. For example, your cable modem might provide NAT. If you then connect an AirPort Base Station to the modem, your base station might provide another layer of NAT.