Screen Sharing is working on LAN but Macs can't connect

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Level 1

16 points

Screen Sharing is working on LAN but Macs can't connect

I have two Macs on a wired network both running macOS Sierra, a MBP and a iMac.

Both are set in sharing preferences for File, Screen and Internet sharing. I have been sharing them on this ethernet network for years. About a month ago this changed.

Now, I can share the iMac's screen from the MBP but cannot connect as a Registered User. I get the interface "shake" which I presume means incorrect password. However, screen sharing just goes straight through so how can this be?

Going the other way, I get the same "shake" when I log into the MBP from the iMac. However, screen sharing is not offered as an option, even though the system preferences are set for this.

If I disconnect the Ethernet and run the network wirelessly I get exactly the same results.

The only connection blocking program that I'm knowingly running is Little Snitch. Switching that off on both computers doesn't change the outcome.

Any idea what I need to do to get the network working fully again?

iMac, macOS 10.12

Posted on Jul 4, 2019 9:51 PM

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Answer 1

TheLittles

Level 10

192,745 points

Jul 5, 2019 8:28 AM in response to Ruadh2

Third Party Security Software - Rid of it

Rid of any third party security software you may have installed, as its reconfigurations may have gotten in the way. Such software is unneeded on a Mac. As for its firewall settings, FTP might have become disabled, and particular port numbers could have become misconfigured. So, rid of any third party security software you have installed, if applicable, as it will just get in the way.

Crossover Cable for Hardwire Connections

I would also try a Crossover Cable, and see if that makes a change in accessibility. It’s a different type of networking cable, with one side of the wires in different order. The colors would be different. So, try one and see how it goes for the file sharing.

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Answer 2

Ruadh2 Author

Level 1

16 points

Jul 8, 2019 4:52 PM in response to TheLittles

TheLittles wrote:

Third Party Security Software - Rid of it

I have no third party security software, except that already listed, Little Snitch. I have Little Snitch turned off on both machines, but ran it for many years on this network without issue.

Crossover Cable for Hardwire Connections

I had a crossover cable, so will have to rummage in the basement and see if I can find it.

Thanks for suggestions.

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Answer 3

TheLittles

Level 10

192,745 points

Jul 8, 2019 5:55 PM in response to Ruadh2

Frankly, it’s the security software.

So, create a Time Machine Backup on the device(s). Then remove Little Snitch. Try this all once more. Recovering from the Time Machine Backup, this software and all else will be right back on the Mac.

So try it.

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Answer 4

Ruadh2 Author

Level 1

16 points

Jul 23, 2019 10:32 PM in response to Eric Root

Eric Root wrote:

Is screen sharing working now?

Eric

Thanks. As of today it is. This is what I tried.

Turned off (but didn't uninstall) Little Snitch - no change. Left off.

Checked for duplicates on the network (suspected because one computer is named "X's MacBookPro (2)"). Found a duplicate, and changed the computer name. No change in connectivity. Changed the name back (since it had worked okay for years).

At this point (yesterday) a number of system upgrades were implemented. My computers are always up-to-date.

After the upgrades I removed file sharing from one computer and then reinstated it.

Afterwards, connections worked in both directions (even though I'd only changed the file sharing on one computer).

So, what fixed it? The system upgrades, Sierra 10.12.6 might have done it. Or just removing then reinstating file sharing, though I'm sure that I did this previously.

Thanks all for your help.

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