FortiGate
FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
kumarh
Staff
Staff
Article Id 339802
Description This article describes that if the FortiGate is acting as a DHCP-relay and if the switch is the downstream device, it is possible to encounter the error 'can't get server id from client message'. The reason is that the PC not getting an IP address.
Scope FortiGate.
Solution

Topology:

PC---------Switch1(vlan451)----------Switch2-----------Port 11 - Fortigate Relay- Port 10 ---------DHCP Server


If enabling the DHCP relay in FortiGate, then run the below debugs and renew the PC IP address:

 

diagnose debug application dhcprelay -1
diagnose debug console timestamp enable
diagnose debug enable

If it is happening, the following error 'Warning! can't get server id from client message' in debugs appear. Make sure in the switch, the DHCP relay is disabled.


The error message 'can't get server id from client message' suggests that the FortiGate is having trouble interpreting or processing the DHCP requests from the client. This could be due to the interference or duplication of relay attempts

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