It is odd!
Could you try pulling console logs from all three failed devices? What console output says?
I would advise to log a case with console logs from all 3 failed devices and let support check further.
An standard flow of troubleshooting should be:
1- Check power adaptor and power source. Is the device powering up?
- Yes = continue to step 2.
- No = Hardware fault = Support case >> RMA.
2- Do you see a stable or flashing red LED on status?
- Yes = Hardware fault = Support case >> RMA.
- No = follow step 3.
3- Check network cable and switch port. Try to use a new cable and connect the ZD to a new switch port and second eth port of the ZD (just in case first Eth port on ZD may be faulty).
4- If above all looks good and still you are not able to access ZD, then follow troubleshooting steps given below in the same sequence (If issue not fixed then continue to next sub step given below):
4.1: Push the 'Reset' button (reset, not FD).
4.2: Reload the power.
4.3: Push the FD button and hold it for 12 seconds and then release it. Detailed procedure can be found here
4.4: Connect console cable (for settings click here
. Article #000004232) >> Reload the power and check the logs on console window. Collect the logs.
5- Open a support case and provide the logs/output to support. Support may provide RMA but if you have multiple devices showing same issue then support can check and get the failure analysis done (Note: Failure analysis takes a lot of time so findings could take time).
Syamantak Omer | Community moderator | Staff TSE | CWNA | CCNA | RASZA | RICXI | Follow me at https://linkedin.com/in/syamantak-omer-5949b6124