DHCP Relay from Wireless network to a specified Interface


I am using the following:

- SG125 with latest firmware 9.713-19

- APX320 (Wireless Access point)

I use the Eth2 on SG125 that is connected to a device that is supplying a DCHP Server. It is required for a new project.

The APX320 is connected to Eth5 and working already for different Wireless networks, but these networks are using the DHCP Server of my SG125.

Now I want to add an additional wireless network on that the connected clients should receive the DHCP addresses from the DHCP Server connected to Eth2.

I tried already different things, like DHCP relay or Ethernet Bridge, but all without success.

Do I overlook a setting for this scenario?

Many thanks for your help!

  • Hallo Ingo and welcome to the UTM Community!

    I'm not "seeing" your topology.

    1. Is there an Ethernet switch involved?
    2. Are you just trying to configure and test the device supplying DHCP?
    3. Is there an existing wireless network bound to the LAN on eth5?

    Cheers - Bob

    Sophos UTM Community Moderator
    Sophos Certified Architect - UTM
    Sophos Certified Engineer - XG
    Gold Solution Partner since 2005
    MediaSoft, Inc. USA
  • Hi Bob,

    1. I have Ethernet switches in use but not on port ETH2 and ETH5.

    2. No. The device is already supplying DHCP. But it is not supplying DHCP for devices connected via the Wireless Network wlan4.

    3. On Eth5 I am using VLANs only. There is no bridge Mode in use.

    For better understanding I try to explain the topology as follows:

    Eth0 - - Connected to Ethernet switch for Computers and Printers
    Eth1 - - WAN to Mobile Internet
    Eth2 - - WAN to Highspeed Internet that is supplying DHCP as well. DHCP range is
    Eth3 - not in use
    Eth4 - - Computer for Conference System
    Eth5 - VLANs 10, 12

    VLAN 10 - - Management Interface for APX320 Access Points
    VLAN 12 - - Management Interface for Network Switches

    wlan0 - - WiFi for Conference
    wlan1 - - WiFi for Crew
    wlan2 - - WiFi for Training
    wlan3 - - WiFi for Engine
    wlan4 - - WiFi for HIGHSPEED INTERNET

    NAT Rules:
    Network: Uplink Interface:
    Ethernet switch Uplink Interfaces
    WiFi Conference Uplink Interfaces
    WiFi Crew Uplink Interfaces
    WiFi Training Uplink Interfaces
    WiFi Engine Uplink Interfaces
    WiFi HIGHSPEED INTERNET Uplink Interfaces

    DHCP Server:
    Name Interface IP Address range Gateway DNS 1
    Management Access Points VLAN 10
    WiFi Conference wlan0
    WiFi Crew wlan1
    WiFi Training wlan2
    WiFi Engine wlan3

    Firewall Rules to allow the required traffic are setup already for all networks.

    Now the devices connected to Wlan4 should get DHCP from Eth2.

    Many thanks in advance!


  • Hallo Ingo,

    Weihnachten ist vorbei, also erst jetzt hatte ich Zeit...

    I think this is simply a case of the wlan4 wireless network needing a different configuration.  Instead of being a Separate Network, configure it as "Bridged to AP LAN" and everything should work as you wish.

    Cheers und Gruß aus Oklahoma - Bob

    Sophos UTM Community Moderator
    Sophos Certified Architect - UTM
    Sophos Certified Engineer - XG
    Gold Solution Partner since 2005
    MediaSoft, Inc. USA
  • Hallo Bob,

    bei mir war es auch etwas stressiger. Aber nun habe ich Zeit zu antworten.

    When I configure it as "Bridged to AP LAN" then the clients in the wlan4 are getting the IP settings from the "Management Access Points VLAN 10". I tried the DHCP Relay function but it does not work as well.

    Best regards from Germany,