Wiz108sr with FF:FF:FF:FF:FF:FF mac address

The MAC of my WIZ108SR board has changed to FF:FF:FF:FF:FF:FF after a factory reset. Although the configuration tool can detect it, I can’t ping it any more. please help me to put back the MAC address (wich is written on the board). My upload is also not working. When I press upload button it says "the destination (I was able to change it) is unreachable. Please check if the device is in the same subnet with PC! " although it is in the same subnet.

Please HELP…

It seems broken data flash.
You need to request RMA.
Contact seller.
They will tell you procedure to request RMA.

My Module WIZ108sr(rev 1.1) have FF:FF:FF:FF:FF:FF mac, the config tool find it but can’t ping it.
I get next lines via serial on module start up:
I can’t upgrade firmware too.Can you help please?

I would like to guide me to solve the problem without sent module back to saler (tme.eu) because of time pressure

Thank you in advance

Best regards


You can recover the mac address by follow steps.

  1. Download and install WIZISP for W7100[attachment=2]WIZISP.zip[/attachment]
  2. Short the pin 1 and 2 of J1 as below.
  3. Turn on power of the WIZ108SR.
  4. Check the COM Port number and Click the “Open” button of the WIZISP.
  5. Check the “Data” radio button of Flash Operation Mode and Click the “Set” button. WIZISP will shows log message as below.
  6. Click the Erase Button.
  7. Close the COM port.
  8. Execute the serial terminal and open the COM port on your terminal.
  9. Reboot the WIZ108SR.
  10. The WIZ108SR will shows message as “INPUT FIRST MAC?” via serial terminal.
  11. Input mac address of WIZ108SR via serial terminal like as “MC00:08:DC:XX:XX:XX”



I encountered a similar problem with my WIZ107SR Serial to Ethernet module. As ywkwon suggested, I followed all the steps. However at step 10 I should be getting a message on the serial terminal asking for the new MAC address. But I’m not getting anything on the terminal. Any suggestions?

Hi, zener.
This recovery solution needs WIZ107SR Full firmware binary (Boot + App) but we’re offering application firmware for update by configuration tool only.
(This is our policy, the entire binary file for WIZ107/108SR products are not disclosed.)

If you have followed this approach, the module can not be recovered.
Please request RMA to place of purchase(or our distributors / branch).


Hi, we have also encountered some WIZ107SR parts (5-pieces) that have been working and then suddenly all the configuration is reset to the factory default settings and the MAC address is set to FF:FF:FF:FF:FF:FF. Is there any information available about the cause of this issue? It is very important to our application that we don’t have sudden failures like this. Is there any steps that we can implement to avoid this behavior? Is this behavior caused by external (Ethernet) input or by serial port activity? Any information would be appreciated.

Hi, rhill
It looks like ‘MAC address broken’ problem.
Please refer to the next link for solving this problem. (find MAC address re-write steps)

I’ve attached new version firmware for WIZ107SR / WIZ108SR, stability improved version.
Please perform the firmware update using this version 4.05.

WIZ107SRv4_05.zip (21.8 KB)

WIZ108SRv4_05.zip (21.6 KB)

Thank you for you prompt response. The tool does allow me to reset the MAC address, however, we have several hundred WIZ107SR devices deployed and we need to know what external factors might induce the “bad MAC address problem” so that we can take steps to prevent this from happening in our deployed systems. We depend upon the device working 24-hours a day, 7-days per week and 365-days per year… If you could give me a recipe that causes the bad MAC problem I could use it in testing my systems. Does the problem occur if I am send data on the WIZNET serial port while power is cycled or a bad Ethernet connection (miss-wired)?

    Does the 4.05 version of the WIZNET firmware completely correct the bad MAC Address problem and how can we test the fix?

Thanks, Ron

Hi, Ron.
According to our tests, the MAC address broken problem occurs when executing the Save function (includes DHCP IP allocation). So, occurrence of this problem is not related to the Ethernet connection.

The Save function stabilization steps has added in firmware version 4.05 for solve this problem, it seems to work well. We are sorry for this troubles. Please try to test by updated new version firmware (attached above).


Thank you for the additional information. Do you know when Version 4.05 will be officially released? We have begun testing internally but probably won’t deploy (upgrade) existing installed devices until it is officially released.

Thanks, Ron

Internally, the new firmware version 4.05 has been released in the past week.
It will be updated today or tomorrow on the our official website, wiznet.co.kr

Both versions (attached version firmware on this post and official released firmware) are the same, so please use with confidence.