Screen share over VPN not working on Mac

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Ken Anderson

• April 19, 2021 13:46

I have a firewalla gold, and a mac on my network I want to access via screen share. I'm using TunnelBlick on the computer that's connecting to the VPN.

When both computers are on the same network, screen share works perfectly. When I try to connect over VPN, I either get connection refused, or the connection is immediately closed.

The firewalls on both macs are off. I have no trouble with DNS - I can ping the computer I want to remote control without issue.

Any ideas?

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  Firewalla

  • April 19, 2021 16:20

  How are you accessing the MAC screen? is it via the MAC IP address? or via the mac's name?  

  Also, check your LAN settings on the machine connecting to VPN, make sure its IP address allocation is different from your MAC at home. 

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  Ken Anderson

  • April 19, 2021 16:35

  I've tried IP and name...DNS resolution is fine - I can ping the machine without issue. When both machines are on the same network, no problem.

  The IP ranges are completely different - I switch to cellular to test.

   

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  Firewalla

  • April 19, 2021 18:36

  Do you have any rules applied to the LAN segment?  Are you using vnc:// to connect?

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  Ken Anderson

  • April 19, 2021 19:26

  The only rules I have is to block gaming at certain times on my sons’ computers and phones.

   

  Yes, using vnc://hostname/ which works fine when the source computer is on the local network, but fails when it’s remote and through VPN.

   

  I’ve also tried routing all traffic through the VPN instead of just the remote network range - doesn’t help.

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  Firewalla

  • April 19, 2021 20:16

  Got it.  This is kind of strange for sure, vns:// is TCP / port 5900.  Can you ping your MAC while on VPN and see if it respond?  Mean while, I'll get someone to test this 

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  Ken Anderson

  • April 19, 2021 22:02

  Yes, no trouble pinging the target. In fact, I can SSH into the target without issue.

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  Firewalla Support

  • April 20, 2021 07:53

  Hi, 

  I tried in lab, with VPN connected via TunnelBlick, by typing vnc://hostname.lan I can access the VNC server.

  How do you set up the VNC server ? if you set up the VNC server on MAC via "system preference" > "screen sharing" ?  you need to follow the instruction in the screen sharing to set the vnc://hostname. 

  Pls see picture below. 

  

   

   

   

   

   

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  Ken Anderson

  • April 20, 2021 13:06

  This is exactly what I'm doing, using the hostname displayed on this panel.

  To be clear, it works perfectly well when both macs are on the same network with the Firewalla. No issues. Then I take the VPN mac off the network, connect to my phone hotspot, and connect via TunnelBlick.

  At this point, I can ping the name of the target machine as shown in the sharing panel, and I can also SSH to that machine. However, when I try to connect via screen share, I get an error that the connection is refused.

  I have tried both with all traffic going over the VPN, and with the typical configuration of just sending the VPN IP range.

  Again, screen share and SSH work when on the network, but when VPN'd, SSH works, screen share does not.

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  Firewalla

  • April 20, 2021 16:42

  Have you tried to VPN without using the hotspot?  Meaning, just VPN inside the same network.  Does that work?

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  Ken Anderson

  • April 20, 2021 18:32

  I hadn't, but I just did. Yes, that works.

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  Ken Anderson

  • August 12, 2022 18:26

  I could really use an answer on this one - it's really hindering my ability to work. Can you please take another look? Maybe give me some troubleshooting tips?

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  Firewalla

  • August 13, 2022 04:20

  We asked you "Have you tried to VPN without using the hotspot?  Meaning, just VPN inside the same network.  Does that work?"

  Also, see if there are any controls that may be blocking remote access to your servers. We know some windows boxes will only allow local IP

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  Ken Anderson

  • August 16, 2022 15:29

  I had replied after your question (above), saying that yes, I hadn't tried, but I did, and it worked. So, yes, it works properly when on the local network.

  I'm all on macs - no windows. I have nothing else but the firewalla.

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  Ken Anderson

  • August 22, 2022 15:03

  Hello?

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