Screen Sharing connection failure

TidBITS Talk
1

Hi friends,

I have a “headless” Mac Studio that I use for email filtering, as a file server, and a few other things. Normally, it just sits and runs quietly without me needing to do anything to it. However, when I do need to fix or do something, I’ll remote into it from my MacBook Pro over the local network. I can currently see the Mac Studio and connect to it via the Finder and browse the various drives, however, I can’t for the life of me establish a screen-sharing connection, something that I’ve previously done a million times.

Both computers are running Mac OS 15.0.1, and are connected to the same network–Mac Studio via ethernet and the MacBook Pro over wifi. I’ve rebooted both computers, and on the Mac Studio I’ve disabled Remote Management and Remote Login, and ensured that I have access in Remote Management, but still get no love.

Any other suggestions?

2

Is the Macbook Pro on a guest wifi by any chance?

You could give Splashtop Personal a try to see if it works: $5 a month or $16 a year.

3

I’m on older systems but my headless Mini often dozes and refuses to wake up. I’ve also found, in the midst of my Comcast to Frontier switch, that it likes to connect to an extender out in the garage for some reason. When it does, I can’t reach it then either.

The other thing I’ve found with both of my machines is that sometimes I have to connect to the hard drive and then ask for screen sharing.

I connect to the hard drive one of two ways: in the finder and clicking on the device (in Column view), and clicking on Connect As

OR if it’s not showing in my list I try Apple-K to connect to my list of recent servers.

Then once connected I hit the Share Screen button.

I also didn’t realize until recently I could open Screen Sharing as an app so that’s what I tend to use now with a bit more success.

Diane

4

For years I have kept an older Mac to use as a file server, curating a disk array with all my ripped videos and photography on it. This was originally a headless MacMini, but after too many difficulties during system updates, it was replaced with a Mac with a screen. Once you have made a ScreenSharing connection you can save the connection using the menu Connection>Save As… and keep the file. I keep it in my documents folder and put an alias in the dock. I do the same for one of the disks in the shared array (the others get a backup of it each day via CCC) and keep an alias in the dock for it too. By giving it a fixed IP address in my router the links stay valid over restarts.

5

In the screen sharing settings, you can specify which users are allowed to connect. Are you connecting to the Mac Studio as one of the authorized users?

If you have the firewall turned on, you might see if disabling it temporarily eliminates the problem.

6

There are some reports of network-related problems with 15.0.1. Some people have them, while others do not. My MacBook Pro is upgraded, but not my two headless Mac minis. I have no problem with Remote Management.

I would try to turn off the “Limit IP Address Tracking.”

I have noted this report from MacRumors forum:

“I have found in Sequoia that setting Ethernet to Inactive and then Active again (System Settings > Network > Ethernet > “Make Inactive” and then “Make Active”) fixes connectivity issues that I have with Remote Desktop in Sequoia 15.1 Beta (24B5055e)."

1 Like
7

Thanks for the suggestions. I gave them a try, but still no love.

8

Yes, I’m the only authorized user.

9

Did you reset both macs?

10

If by “reset” you mean “restart,” then yes. The MacBook Pro is on wifi, so I can’t reset the ethernet on it.

11

Sorry, on Wifi I mean forget and setup again.

12

No, I’ve not done that, but it’s worth a shot, though I can connect to the Mac Studio and move files back and forth in the Finder.

13

Some people have no problem with file sharing, but ssh does not work. That is the reason I am reluctant to upgrade my headless macs.

14

Isn’t there some sort of HDMI dongle you need on a headless Mac to screen share with it? It was discussed a bit in this thread.

15

Yep, I have a dongle when I’m 100% headless, but right now I have my display connected so that I can make changes and adjustments to the Mac Studio. Remotely connecting to the Mac Studio with the display connected normally works, but it’s not right now.

16

I use this one from Newer that I purchased at One World Computing, currently at $12.99 each:

I also bought some “cheapies” from Amazon and those seem to work too.

17

I’m not on Sequoia, and I’m not on my Mac right now, so this is some general suggestions. YMMV…

As far as I can remember, screen sharing requires:

  1. The screen sharing daemon must be running on the host. Is this sharingd?
  2. Host IP address and port needs to be open in firewall(s). The macOS firewall should do this automatically, others may require configuration. I think it uses the same port as VNC (TCP 5000).
  3. Client must have right IP address for the host
  4. Must be able to reach that IP address and the sharing port
  5. If all of this is OK, the last hurdle is authentication

It should be possible to test if your guest can reach the host at the IP address and port.

If it is an authentication issue, a long time ago I hit a problem where it didn’t work until I removed the Administrator group from the screen saver settings and then added it back again.

18

Since @TallTrees are able to access files via filesharing, we know that he are able to reach the IP address. The port is 5900. Try nc -zv <remote_mac_ip> 5900 in Terminal.

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19

I use Screens to login to my headless but sometimes it doesn’t work and sometimes unloading/loading screensharing fixes it, assuming you can ssh in

sudo launchctl unload /System/Library/LaunchDaemons/com.apple.screensharing.plist
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.screensharing.plist
1 Like
20

The fact that it worked before and now you anre running macOS 15.0.1 rings very familiar to me. I have been using Time Machine to back up my MBP to a drive attached to a Mac mini forever — that was until October 3 when I updated both from 15.0 to 15.0.1. Worth noting: My wife’s iMac continues to TM backup without issue (it isn’t the mini).

After hours of debugging (wired vs Wi-Fi, Safe Boot mode, new/virgin login account, delete and restart the TM backup fresh, etc.) I finally called Apple. After working with three Advisors I know now that 15.0.1 introduced a bug in the Firewall. Turning it off allows the TM backup to complete.

So, I recommend that you turn your firewall off and see what happens.