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DNS Server in DHCP options keeps changing to Sophos IP

Hi All...

Customer has XG135 (SFOS 19.5.3 MR-3-Build652), Sophos is the main DHCP server for the network, for the last few months we have been battling with a strange issue.

Sophos LAN IP is

Internal Microsoft DNS server

DHCP on the Sophos is configured to use for the DNS, Randomly the Sophos will change the DNS server to itself ( - Causing DHCP clients to get DNS which then causes issues with internal DNS resolution.

Multiple support tickets opened with support- the keep wanting to read logs and to tell them when it happens- no actual help to resolve this.

Customer does have multiple static reservations configured on Sophos DHCP.

Anyone had this issue before or have any suggestions?

Edited TAGs
[edited by: Erick Jan at 7:03 AM (GMT -7) on 29 Mar 2024]