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Client DHCP Timeout when clock inaccurate

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  • 1.  Client DHCP Timeout when clock inaccurate

    Posted 2 days ago

    The Apple devices we receive come in with their time set to PST and we are in EST. When connecting them to the device enrollment SSID we have, they will get "Client DHCP Timeout" errors.

    Connecting these devices to the wired network that shares the same DHCP server is working as expected. We are also migrating to Central, and on our local controller hosted APs it is working as expected as well.

    Is there something in Central that has a time difference tolerance to cause the DHCP request to timeout?



  • 2.  RE: Client DHCP Timeout when clock inaccurate

    EMPLOYEE
    Posted 2 days ago

    Can you please open that message to see which DHCP Server will be used?
    What is the Wi-Fi Connectivity saying in combination with AI Insigths?




  • 3.  RE: Client DHCP Timeout when clock inaccurate

    Posted 2 days ago

    That is the correct DHCP server.




  • 4.  RE: Client DHCP Timeout when clock inaccurate

    Posted 2 days ago

    Also, Did apple device finished 802.1x authentication or use pre-share key?

    did you try using a different SSID only with pre-share key in order to validate that DHCP it is OK?

    When use other device (android, windows) works as expected?




  • 5.  RE: Client DHCP Timeout when clock inaccurate

    Posted 2 days ago
    This is on an Open network with no .1x or PSK. Devices that have their clock correct have no issue, neither do wired devices using the same DHCP server.

    --
    Matt Fogleman
    Network Administrator
    Unionville-Chadds Ford School District
    (o)  (610) 347-0970 x3332

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  • 6.  RE: Client DHCP Timeout when clock inaccurate

    Posted 2 days ago

    Hi Matt.

    I´m not expert on DHCP server settings. Maybe the logs from the dhcp server tell us more information about:

    1. the request reaches the server.
    2. if the server responds to the client.
    3. Take a packet capture on the controller if the SSID is on tunnel mode or from Central.

    Also, you can test other dhcp server (switch core) and check if the behavior persists.




  • 7.  RE: Client DHCP Timeout when clock inaccurate

    Posted 2 days ago

    Yeah I don't think it's the DHCP server since the same exact device if plugged into ethernet will get an IP address fine from the same DHCP server. It also works on SSIDs on our controller based WiFi from the same DHCP server.




  • 8.  RE: Client DHCP Timeout when clock inaccurate

    EMPLOYEE
    Posted yesterday

    In the message is stated "Client Offer timeout" means the infrastructure has seen the offer by DHCP Server but the Client did not acknowledge.
    I doubt that is has something to do with PST or EST. When I am in the US with my Device sets to CET it also works in another timezone.
    Question now is why the Apple Device (all or just a couple?) don´t acknowledge the DHCP Offer.

    I would use the PCAP option in Live Events and analyse the PCAP in Wireshark to see if the Client is reacting on the offer.

    Server send NAK could be caused by a) Client is requesting an IP Address which is in use by another Client or b) because the IP Scope has no IP Addresses available.
    Another Question, do you use RFC4833 in DHCP Server? This is an option where you can give Timezone information via DHCP to the Client. DHCP Option 100, 101
    DHCP option 100: time zone POSIX string as in IEEE 1003.1
    DHCP option 101: time zone as a string like in the TZ database (eg: Europe/Paris)
    Maybe Apple has an issue with that.
    https://support.apple.com/guide/iphone/change-the-date-and-time-iph65f82af3e/ios#:~:text=Go%20to%20Settings%20%3E%20General%20%3E%20Date,automatically%20determine%20the%20local%20time.