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Hello.

I must've changed something in between OS updates and I don't remember. Three months ago I could connect every computer in the LAN network with Screen Sharing by simply clicking on it in the Finder.

Now, all I get is a message saying:

My Stupid Computer wrote:Unable to communicate with “Symmetrical Diminished”. Make sure the remote computer is available and the firewall is not blocking screen sharing.

I am connected via 2 different networks. 1 is a LAN and the other is the WiFi network. Screen Sharing doesn't work under any of them.

-- My Firewall is NOT set to stop SS. It actually explicitly allows it, as shown in the first half of the relevant preference window.
-- Cable is fine because I can use Folder sharing between the computers without problem.
-- I've also tried, to no avail, creating a new network location

... all that applies to all the computers...

Is there a particular preference I should delete? I really don't know what to do, and I REALLY need Screen Sharing to work.

I haven't found anything useful via Google... only unrelated WIFi stuff.

Thank you.

I'm shooting in the dark here but I'd start with this.

https://support.apple.com/kb/ph25571?locale=en_US

Are all the OSs the same? My success in getting screen-sharing to work has been limited unless the OSs are in parity. ...that’s all I got.

I've been having problems like this for a long time, and they got worse with HS.

One thing that sometimes works: a) remove all the references to IDs and PWs in the keychain, b) go to the Network folder in the Finder and create the connection again, using the Share Screen buttons, and tell it to save the passwords.

I've noticed that if a Mac has been running for some time, say several hours, it will sometimes "disappear" from the network, or sometimes devices attached to it will appear on it's Finder, but not on the Finder of another Mac attached to it. Restarting the "hidden" Mac will usually fix this.

Following Mike's advice to do a safe startup seemed to help for a few days.

This stuff seems to come and go randomly, and it gets really tiring after a while.

dix wrote:Are all the OSs the same? My success in getting screen-sharing to work has been limited unless the OSs are in parity. ...that’s all I got.

? The only connection I can get with absolutely no glitches is to view the screen and files on a Mini running 10.6.8 from other Macs running a few different versions from 10.10 to 10.13.

I ignored this topic at first, as I only have one computer at home, but then remembered it's more or less the same problem I've had for a year (or a bit more) with my work computer.

Ironically, I can only use my Mac at home to connect to my Windows box at work vs. my Mac at work. Our IT department is very Windows-centric so I've been on my own on this issue, and gave up as I have much higher priorities (and things/problems I'm behind on).

It now occurs to me, based on the discussion here, that the problem may be due to having upgraded to High Sierra at work, but not yet at home, and similarly having not been on Sierra at the same time either (as I upgraded to Sierra at home, at the same time that I updated to High Sierra at work).

When I was on whatever came before Sierra (can't remember if that was El Capitan), consistently at both home and at work, Screen Sharing always worked and never reported weird/incorrect errors.

mhschmieder wrote:It now occurs to me, based on the discussion here, that the problem may be due to having upgraded to High Sierra at work, but not yet at home, and similarly having not been on Sierra at the same time either

I have always had between 4 and 6 Macs here, all on the same LAN. They have usually all been on different versions of OS X, and the success of screen sharing has never been dependent on which versions the Macs have and whether the are different. Screen sharing in general has usually worked better than file sharing. I have had instances where I've had screen sharing up, but the Finder reports that drives on the same Mac cannot be found for purposes of file sharing. In these instances, I could even open a folder on the Mac displayed in Screen Sharing, and drag and drop files to that folder from another Mac, even as the Finder tells me the drive I am copying to cannot be found by file sharing.

Woops. I can't believe I forgot my own thread. I'm not getting emails to remind me of the topics anymore.

Anyway, after hours and hours of wasted time, trying everything I read on the net, I gave it up. It simply didn't work. Nothing worked. I think I might have deleted a few plists that I forgot about, and it just didn't work.
Oh, and the Apple fora are so useless!

Then, somewhere, I stumbled into a random post, a few days ago, that simply suggested updating Remote Desktop app via Apple Store. It was there already waiting for me in all my computers. I downloaded it, and, as if by some magic, ALL my computers work with screen sharing again.

This update must've rewritten some of the plist files I had deleted, or it overwrote some corrupted files. The weird thing is that all my computers stopped working suddendly, and they all started working after this Remote Desktop update suddenly too. Weird...