Airport Express and DNS Problems

Discussion in 'Mac Accessories' started by wildbill, Aug 7, 2008.

  1. wildbill macrumors newbie

    Jun 7, 2007
    I am having an odd issue which I was hoping someone might be able to help me out with. Here is my setup:

    -Airport Extreme connected to my modem.
    -Airport Express connected to a PC upstairs using the ethernet port.
    -Airport Express "extending" the Extreme's wireless network.

    This has been my setup for a few months, and everything has been rosy till about 2 weeks ago.

    So everything connected to the Extreme using a wired connection works just fine. What happens with the Express is that after a certain amount of inactivity (or could just be an amount of time), I can no longer reach the web anymore. Other services such as IM work, but the the PC cannot connect to the web anymore. So I thought it must be that it cannot find the DNS servers anymore for some reason. So instead of letting the Extreme or the Express trying to find them automatically, I manually entered them using the Airport Utility. That didn't help fix the problem. I tried doing a hard reset and starting from scratch on the Express, and that didn't work.

    The only thing I've changed recently on the Extreme was set the IP address setting to "Share a Single IP Address", under the Internet tab. It was on the other setting (NOT the bridge mode, but the other setting. The wording of that setting escapes me right now), and I was getting some funky IP addresses assigned, which made me think that I had my configuration messed up. I know y'alls first question will be have you tried putting it back the way it was, and that's the one thing I haven't tried yet, because I would like to avoid that if at all possible.

    If I unplug the Express, and plug it back in, it works for awhile before it goes down again. This isn't like other problems I've searched for, because I can still see the Express in the airport utility, and once I unplug and replug it in, it works just fine.

    Any help would be appreciate, because I am out of ideas. Thanks!
  2. andimaciphone macrumors member


    May 9, 2008
    Question to clarify setup?

    I am a little confused or am misreading your post.

    Have you got one or two airport express in your network?

    It looks like two but you only refer to one express in your problem.
    I know y'alls first question will be have you tried putting it back the way it was, and that's the one thing I haven't tried yet, because I would like to avoid that if at all possible.

    So what are you trying to achieve then?
  3. wildbill thread starter macrumors newbie

    Jun 7, 2007
    I have one Extreme, and one Express. The Extreme is on the main floor of my house, and the Express is on the top floor. The PC I am having trouble with is hooked to the Express using the ethernet port, and the Express is extending the Extreme's wireless network.

    The reason I changed that setting is because when I had it on the other setting, I was getting external IP address assigned to my hardware on my network, so it seemed as I was opening myself to security threats, people being able to see my machines outside of my internal network, etc. The setup I am trying to achieve is having one external IP address given from my ISP (which is a WISP), and then all my hardware being assigned internal IP address by the Extreme (i.e. 10.1.1.x).

    The way I have it setup now seems to be what I am trying to achieve, except for the Airport Express getting messed up as described above.

    Does this make more sense?
  4. andimaciphone macrumors member


    May 9, 2008
    Makes more sense now thanks

    Right I am clearer now Bill.

    You have a similar setup to mine that I set up last weekend.

    This is what I did.

    Equipment used:
    1. Netgear Router connected to ISP
    2. Time Capsule
    3. Airport Express

    This is the process I went through:-
    1. Connected the Time Capsule (Airport Extreme) to the router
    2. Then opened Airport Utility to configure Time Capsule
    3. Then setup a new wireless network
    4. I allowed this network to be extended - letting the Express onto and extend the network
    Then I set the Express up to extend my wireless network.

    The only difference here though is that all of my devices connect wirelessly, not wired.

    Is there anyway that your PC can join wirelessly?

    Actually, have you tried setting the Express to join the wireless network ie act as a client?

    The reason I say that is I think that the ethernet port doesn't work if it is acting as an wireless access point, I will check that out and post back in a few minutes.
  5. andimaciphone macrumors member


    May 9, 2008
    Extract from Apple Manual


    This is extracted from one of Apple's manuals on Airport networks that I think will help you.

    To share a single Internet connection with AirPort computers and computers
    connected to the base station with Ethernet using DHCP and NAT, choose “Share a
    public IP address” from the Connection Sharing pop-up menu. Using DHCP and NAT
    lets the base station dynamically and automatically assign IP addresses to client
    computers, which simplifies each computer’s TCP/IP configuration. See “Setting
    DHCP and NAT Options” on page 31.
    By default, the base station allows devices and computers using Ethernet and
    computers using AirPort to communicate with one another using non-IP protocols
    like AppleTalk. If you want to connect an AppleTalk Ethernet printer to the base
    station or use AppleTalk between wired and wireless computers, make sure the
    devices are connected to the Ethernet LAN port (G) on the base station.

    The quote from p.31 is here:-
    Choose a range of IP addresses from the DHCP Range pop-up menu. Choose 10.0,
    192.168, or 172.16 and then enter a beginning and ending address in the DHCP
    Beginning Address and the DHCP Ending Address fields, depending on which
    addresses you want the base station to provide.
    Â Enter a number in the DHCP Lease field, and then choose minutes, hours, or days
    from the pop-up menu.
    Â Type a welcome message in the DHCP Message field. This message is displayed when
    a computer joins your network.
    Â If your network is set up to use a Lightweight Directory Access Protocol (LDAP) server
    on your network, you can enter the address of the server in the LDAP Server field,
    and computers on your network will have access to it.
    Â To provide specific IP addresses to specific computers on your wireless network, click
    the Add (+) button below the DHCP Reservations list, and follow the onscreen
    instructions to name the reservation and reserve the address by MAC address or
    DHCP client ID. If you choose MAC address, click Continue and enter the MAC
    address and specific IP address.

    Next you can set NAT options for the network. Click NAT.
    Â You can set up a default on your network. A default host (sometimes known as a
    DMZ) is a computer on your network that is exposed to the Internet and receives all
    inbound traffic. A default host may be useful if you use a computer on your AirPort
    network to play network games, or want to route all Internet traffic through a single
    Â You can set up NAT Port Mapping Protocol (NAT-PMP). NAT-PMP is an Internet
    Engineering Task Force Internet Draft, an alternative to the more common Universal
    Plug and Play (UPnP) protocol implemented in many network address translation
    (NAT) routers. NAT-PMP allows a computer in a private network (behind a NAT router)
    to automatically configure the router to allow parties outside the private network to
    contact this computer.
    Included in the protocol is a method for retrieving the public IP address of a NAT
    gateway, allowing a client to make this public IP address and port number known to
    peers that may wish to communicate with it. This protocol is implemented in current
    Apple products, including Mac OS X 10.4 Tiger, AirPort Extreme and AirPort Express
    networking products, and Bonjour for Windows.
    You can also set up port mapping. To ensure that requests are properly routed to your
    web, AppleShare, or FTP server, or a specific computer on your network, you need to
    establish a permanent IP address for the server or computer, and provide “inbound port
    mapping” information to the AirPort Base Station.

    Not really sure if that helps or hinders.
  6. wildbill thread starter macrumors newbie

    Jun 7, 2007
    andimaciphone, sorry I haven't gotten back to you sooner, I was out of town for the weekend. I am going to try and do some of the things your posts suggested this evening and I will let you know how it turns out. Thanks a lot for your help!
  7. Consultant macrumors G5


    Jun 27, 2007

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