Q: Screen Sharing to Device with iCloud

What model Macs you are using? Describe which one is the remote Mac you're trying to access, and the one you're using to access it. Did you try toggling Back to My Mac on each one?

I've also upgraded the Server service running on the host machine I'd planned to connect-to

I'm not sure what you mean by that. What was it that required an upgrade?

If you changed nothing other than to update your client Mac to Yosemite, what you describe strongly resembles an earlier bug making an encore appearance.

What follows is what I had to say about it roughly a year ago, updated for today. Some of it will be obvious to experienced Mac users so overlook that.

This can be a challenging problem to diagnose. It appears that Mavericks Yosemite has changed something about BTMM resulting in it being less reliable than it was with Mountain Lion Mavericks. It works, but not always, and I have yet to correlate its cause to anything specific.

Here are some possible hints.

Make sure you are using a compatible router. BTMM requires a router that supports NAT Port Mapping Protocol (NAT-PMP) or Universal Plug and Play (UPnP). Most routers will work without any trouble at all, but an Apple AirPort will eliminate any uncertainty.

Review all the steps in OS X: Using and troubleshooting Back to My Mac with your iCloud account

The most useful suggestion may be the simplest:

• Toggle Back To My Mac off and back on by deselecting and then reselecting Back To My Mac in iCloud System Preferences.

Sometimes that's all it takes.

You can also try some simple steps with Terminal to verify that your BTMM settings are correct:

dns-sd -B _rfb | grep icloud

That will show the Macs using your iCloud ID advertising screen sharing services. If you get no response, ensure the Sharing services on the Macs you wish to use remotely are configured correctly. Perhaps Mavericks simply reverted their settings during installation, as a "security" measure.

dns-sd -B _afpovertcp will show Macs advertising file sharing services.

To ping your Mac use:

ping6 <macname>.<nnnnnnn>.members.btmm.icloud.com

where <macname> is the name of your Mac and <nnnnnnn> is your Back to My Mac account number. See below. You should get a response from ping6; if there is none then screen or file sharing will not work. If the response times are excessively long then the connection may time out and fail.

The name of your Mac is in System Preferences > Sharing > Computer Name:

Your Back to My Mac account number can be determined with the following

dns-sd -E

It will respond with something like this

Timestamp    Recommended Registration domain

0:43:20.322  Added    (More)              local

0:43:20.322  Added    (More)              icloud.com

                                            - > btmm

                                            - - > members

                                            - - - > 0123123

0:43:20.322  Added                          icloud.com

                                            - > btmm

                                            - - > members

                                            - - - > 987654321

The numbers at the end (0123123 etc) are your BTMM account numbers. Most users will have only one.

^C to terminate each of the above.

Good luck.

An example of the above is as follows. Assuming your iCloud ID is 123456 and the Mac you're trying to connect to is named MyMac the above ping6 command is

ping6 MyMac.123456.members.btmm.icloud.com

You should get a response.

You can also try to login to the remote Mac using ssh. Assuming your login name is telstar that would be

ssh -l telstar MyMac.123456.members.btmm.icloud.com

Both should work regardless of your location, whether both Macs are on the same LAN or separated by thousands of miles makes no difference because they are using iCloud services and not local Bonjour to access the remote machine.

Given that your Mac is not appearing in a Finder Sidebar under "shared" I doubt either of the above will work for you.

Report it to Apple. The problem may be related to the particular model Mac you are using, or not.

That's all I have to offer.

interesting . i can Share Screen with two other computers in my area at the moment. But neither ssh -l nor ping6 gets any results.

ssh -l fred fred’sMacMini.12345678.members.btmm.icloud.com

ssh: Could not resolve hostname fred\342\200\231sMacMini.12345678.members.btmm.icloud.com: nodename nor servname provided, or not known

ping6 iMacHome.12345678.members.btmm.icloud.com

ping6: getaddrinfo -- nodename nor servname provided, or not known

ongoing observations;

I had my MBP at work. Screen Sharing was on. On my Home computer, an iMac, in the finder I could not see my MBP under Shared in the left hand pane of the Finder. 

But before leaving work i made note of this info under System Prefs > Sharing:

"Other users can access your computer's screen at vnc://d142-058-130-XXX.burn.sfu.ca/ or by looking for “MBP_HD” in the Finder sidebar. "

I clicked on that link ( changed for security reasons) and i managed to Share Screen with the work computer form home.

This is strange as why does it work with the url but not from with the Finder.

It may   have to do with my ISP and the way they allocate  DNS  ...

This definitely looks and smells like a Yosemite problem, as BTMM stopped working without my touching my home router and only after the Yosemite upgrade,  I usually connect to my home computer from work and not vice-versa, and I see in the ICloud settings on my home computer that there is a problem and it says the DNS Server is not responding.  At work, however, using the same brand of router as at home, and will Yosemite installed as well, I get no error messages in BTMM and everything looks like it works.  I can also ping my home computer from the Terminal as shown above but can not access the computer in Finder.  Very strange mix

I'm not sure how to make the 'Share Screen' button appear, but you can accomplish the same thing with this command:   open vnc://<UserName>:<Password>@<ComputerName>.<BtmmID>.members.btmm.icloud.com   So a trivial example would be:  open vnc://John:mypassword@mymac.123456789.members.btmm.icloud.com  As others have mentioned, you can get your btmm user id with the following command:  dns-sd -E    (After you get the ID, you'll have to use ctrl + c to break out of the dns-sd command in terminal)

Unfortunately, the open vnc command will probably not work if your 'Share Screen' button isn't showing, although there have been a few times I've been able to connect that way when I couldn't via the GUI, so it's at least worth a shot.  Unfortunately I've been struggling with this issue ever since the switch from Mountain Lion to Mavericks.  That update contained a lot of networking changes, so I'm guessing that's why.  It's really frustrating, but I've all but given up hope on a fix after close to 2 years of issues. 

John, this was very educational. It did not solve my issue but I found it interesting to learn.

BTW, what's the best way to use the commands above if you have spaces in your Mac's name.. "My Older Mac 16/500" for example?

IMRAN wrote:

 

BTW, what’s the best way to use the commands above if you have spaces in your Mac’s name.. “My Older Mac 16/500” for example?

In Terminal, type:

dns-sd -L "<Name of your mac>" _rfb <nnnnnnn>.members.btmm.icloud.com 

where <Name of your mac> is the full name of your Mac (i.e., with its spaces, accented characters, etc.), _rfb is the service for which you are querying a list of available remote Macs (in this case Screen Sharing, but you could use _smb for SMB File Sharing instead) and <nnnnnnn> is your Back to My Mac account number.

If <Name of your mac> was, for example MacBook in the attic, the response would be something like this:

Lookup MacBook in the attic._rfb._tcp.<nnnnnnn>.members.btmm.icloud.com
DATE: ---Wed 07 Sep 2016---
13:38:23.320  ...STARTING...
13:38:24.239  MacBook\032in\032the\032attic._rfb._tcp.<nnnnnnn>.members.btmm.icloud.com. can be reached at MacBook-in-the-attic.<nnnnnnn>.members.btmm.icloud.com.:5900 (interface 0)

telling you that the domain which MacBook in the attic would be reachable at is MacBook-in-the-attic.<nnnnnnn>.members.btmm.icloud.com.

In general, therefore, you can just change spaces with hyphens, but the command above will help you if your Mac’s name is more complex than that.