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DHCP Lease Times for Static IP Addresses

Don Fisher1

Hello Everyone.

I have recently reworked my entire network and as I have worked out the last few bugs, I have run into something that I am not able to figure out.  I generally assign static IP addresses to everything that is 'permanent' to my network.  Maybe unnecessary, but I have an OCD thing and I have to be able to recognize everything on my network easily and know where it is (by address).

In my old setup with UTM9, I never had any issues but now I am running XG and my network hardware is different.  The issue I am having is with my IoT segment.  I have a bunch of smart light switches that I have put on their own VLAN for performance and security reasons and once the DHCP lease is up, the devices will disconnect from the network and are not able to reconnect on their own.  If I power cycle them, they do not have any trouble connecting.

Previously, I had a Netgear router in AP mode handling this traffic and with the UTM 9 it never had an issue.  I have replaced the Netgear router with a couple of Netgear business AP's in a mesh and of course replaced the UTM 9 with XG.

For testing purposes, I set the DHCP lease to expire every 10 minutes and then I power cycle every device.  I can see the XG provide a new lease to each device as soon as it reconnects to the network, and once the lease expires, I can see a new lease but the device is disconnected.  When I go to the logs in the AP's, I can see the device disconnect and the next message indicates that the client is unable to obtain an IP address.  It shows as connected to the AP, but no network.

I guess my question is - can I set the lease for static addresses to never expire?  If not, does anyone have any idea what would prevent the device from reconnecting when the lease expires?  I have made every configuration change possible on the AP's like turning on/off all the different radio frequencies, changing channels, changing the authentication method (WPA2, WPA3, etc) and have had no luck.

Any advice is greatly appreciated.  I can add all the network particulars and firewall setup if y'all think it would help.

TIA,

Don F.



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  • 0

    i would try to test the "Netgear router in AP mode" to check if the problems comes from sophos or netgear.

    i use XG with Sophos AP and DHCP without any problem.

    If you connect a mobile device or notebook within this WLAN ... the problem exist too? Possible to capture the DHCP traffic?


    Dirk

    Systema Gesellschaft für angewandte Datentechnik mbH  // Sophos Platinum Partner
    Sophos Solution Partner since 2003
    If a post solves your question, click the 'Verify Answer' link at this post.

  • 0 in reply to dirkkotte

    I only have issues with these particular devices.  Laptop, phone, media streaming devices, etc. all have no issue with this network segment.  If I use a different AP, the issue goes away, but I do not want to keep the old hardware on my network.  I don't think the problem is JUST the AP's, as there are a few of the devices that connect and reconnect without issue.

    Do you know of a way to make the static lease never expire?

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  • 0 in reply to dirkkotte

    I only have issues with these particular devices.  Laptop, phone, media streaming devices, etc. all have no issue with this network segment.  If I use a different AP, the issue goes away, but I do not want to keep the old hardware on my network.  I don't think the problem is JUST the AP's, as there are a few of the devices that connect and reconnect without issue.

    Do you know of a way to make the static lease never expire?

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