screen sharing doesn't work when behind a router

Discussion in 'Mac Basics and Help' started by motulist, Apr 25, 2008.

  1. macrumors 68040


    Dec 2, 2003
    I was setting up a powerbook for my Mom when both computers were at my place and connected directly to my DSL, and I set it up so screen sharing worked perfectly. I bypassed ichat and did it directly though through the Finder's "connect to server" function and typing in the VNC:// address listed in her system pref's screen sharing section that said her screen could be reached at VNC://110.2.random.numbers, and it worked perfectly.

    Then I gave it to my mom and set up an airport express network at her house and then screen sharing wouldn't work. The vnc address that her screen sharing system pref is listing sounds incorrect to me. It says 'Other users can reach your computer at vnc://10.0.#.# (where each # is a single digit).' That sounds like it's probably just a local address, not an actual net address.

    Is this a port forwarding issue?

    - Her connection is through an airport express base station.
    - 'Allow All Incoming Connections' is checked in the firewall system pref.
    - Screen sharing is turned on in the sharing system pref.
    - 'Allow All Users To Connect' is checked on in the sharing system pref.

    How do I make this work?
  2. macrumors 6502a


    Oct 3, 2007
    If you connect from the "outside" of the network using DSL, you will need two things:

    -portforwarding, to make sure the connection will be sent to the mac by the airport
    -a way to contact the airport from the "outside" (dynamic DNS address, which is set up in the airport or with a software, or a fixed IP address)

    Usually the airport get an IP address from the ISP. If it's a fixed address you will be able to use it directly and you will just need to set up the portforwarding. If it's a dynamic IP address (that is it changes from times to times) you will need the dynamic DNS, that will associate a fixed address to you changing IP (it will update the IP associated with the address every time it changes).

    By the way, what do you mean with connected directly to the DSL?
  3. macrumors newbie

    Apr 25, 2008
  4. macrumors 603


    Apr 29, 2005
    San Francisco
    If both machines are on the same network (wireless or not) then it is not a port forwarding issue. Rather I think the Sharing prefs aren't setup correctly. You need to have Remote Management turned on. But that is odd if it was working and now isn't. Perhaps check the AExpresses firewall.
  5. macrumors 68030


    Mar 13, 2007
    Also, if you both setup iChat accounts, I've found it to be a lot easier to get screen sharing working with that, since you don't need to open ports on the routers or local firewalls.

    I support my Mom, and with a simple iChat connection, I can share her screen to help her out. Works pretty well so far.

  6. macrumors regular

    Mar 8, 2007
    Or you could just use it within iChat, in which case it is idiotproof.

    I support my mom also. funny. She has a macbook, I have a mbp.

    I set her up with an aim account prior to even calling her. I emailed instructions to her with her aim account. I called her on the phone and within 5 minutes we were video chatting with screen sharing.

    I'm done with the "the clickie thingie button on email is missing."

    Additional benefit is she gets to see live video of her new grand daughter every day

  7. macrumors newbie

    Dec 5, 2008
    Screen sharing


    I am also trying to get screen sharing to work from Mac #1 to Mac #2. Mac #2 is on a home network behind a Westell router, and Mac #1 is on the internet.

    I am using DynDNS to get the router's ip address, and I have enabled screen sharing on both Macs.

    I understand that I need to forward port 5900 from the router to Mac #2 -- but the router apparently needs to know the ip address of Mac #2. This address is assigned by DHCP and presumably will change.

    Is there a way to forward the port *without* assigning Mac #2 a static ip address? I believe that assigning Mac #2 a static ip address will cause it to not work if it moves to a different network that uses different ip ranges, right?


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