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Losing DHCP Gateway

This problem started with 17.5.0 GA.  The firewall is handling DHCP for my lan.  Users have started to lose the default gateway(the Firewall) randomly throughout the day.  I have to either reset the switch or the desktop network adapter in order to regain internet connectivity.  This does NOT happen to all users at the same time.

I updated to XG 115 SFOS 17.5.5 MR5 but the problem still exists.  This actually introduced another problem of not being able to access the gui from Sophos Central, but that's not as pressing.  Any thoughts on this would be appreciated.



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  • Hi All,

    Thank you for your regress feedback & support

    With MR6, we have been closed with JIRA ID NC-46351, which was earlier reported. 

    We are working on the JIRA ID NC-48031, till now please use the CLI to switch the DHCP old config generate method.







  • Hi,


    for me the cli command did not helped - the DHCP actually gives me default gateway and DNS IP adressses for the wireless clients, but still no internet connection available for them. All of the wireless clients are affected. (TV, laptops, wifi extenders, etc)


    I also noticed that on the interface tab my default gateway which is facing towards the internet is showing status a big red dot. 


    The wired or virtual Network clients are able to use he connection without any issue and connecting to the internet.


    It started to happen only today. The upgrade was done to MR6 a week ago aproximatelly.


    The firewall is running on Hyper-V. Rebuilding the DHCP did not helped.


    I have another XG home on phyical machine which was upgreded same time and have same configurtaion, but that did not experience this issue.


    Any ideas what I can do?


    red color: guest WLAN

    Green color: LAN/WLAN intranet

    blue color: internet

  • Actually i rebuilded the XG Firewall on Intel hardware (and finished with the Hyper-V one) with the latest firmware and its working without any issue.

  • Hello

    Just curious.  What version of Hyper-V (on server 2019 by chance ?) and which intel adapter ?

    Paul Jr

  • Hi Paul,


    it was on Windows 10 1903 and had 3 adapters. If I just remeber correctly perhaps it is get wrong after the upgrade. Till then it was fine.


    Realtek Gbit Ethernet adapter - this was the WAN port

    TP-LINK Gigabit PCi Express dapter - this was the LAN port

    ASIX AX88179 USB 3.0 to Gigabit Ethernet Adapter - this was the Public Wifi port


    Hyper-V configuration version 8.0


    For me the resolution was to install the latest firewall firmware to Intel HW:

    and added to PCIe cards: TP-LINK Gigabit PCi Express dapter and Samsung 120GB SSD


    on this HW the issue is not present. everything is fast and working well.

  • OK

    Realtek uses their own silicon.  TPlink were using Intel at a point of time.  And I have no clue what ASIX is using.

    You could you use a dual port or even quad ethernet adapter in PCIe 1X.  Depending on the motherboard you are using, it may not be possible to use 4, 8 or 16 lanes ... That said, dual or even quad ports are very cheap on e-Bay.

    Paul Jr

  • Is this for Sophos XG hardware, white box, or both?