In our office, I have connected 2 D-LINK (DGS-1210-52 and DGS-1210-24) switches with SFP cable.

The problem is that the devices that are connected through DGS-1210-24 don't get IP address in the same subnet with the devices that are connected through DGS-1210-52.

I tried and I connected the 2 switches with UTP cable and the above problem is gone.

So, why is this happening when I connect the 2 switches with fibair?

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  • Could you post the configuration of your switches?
    – user36472
    Commented Feb 16, 2018 at 12:42
  • Where is your DHCP server?
    – Zac67
    Commented Feb 16, 2018 at 13:14
  • I haven't done any special configuration in the switches. The DHCP server is enabled on the router..
    – yaylitzis
    Commented Feb 16, 2018 at 13:16

1 Answer 1


Well.. Cown asked the configuration of the switch and I responded that I haven't done any.. This was the dark point..

In the switch DGS-1210-24 settings the DHCP Auto Configuration was disabled by default.. The manual of the switch writes that:

This window allows you to enable the DHCP Auto Configuration feature on the Switch. When enabled, the Switch becomes a DHCP client and gets the configuration file from a TFTP server automatically on next boot up. To accomplish this, the DHCP server must deliver the TFTP server IP address and configuration file name information in the DHCP reply packet. The TFTP server must be up and running and store the necessary configuration file in its base directory when the request is received from the Switch.

I enabled it and all works fine...


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