Zyxel NR7101 stopped working

Installing and Using OpenWrt
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After many months of happy usage, randomly my Zyxel NR7101 stopped working. No power light and disconnecting and reconnecting PoE cable (inside of house wall) makes no difference. What gives? Mice chewed through cable?

Any ideas @bmork? Ever encountered anything like this?

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Take the device and connect it to a poe source that is known to be working using a known good (short) cable. If it still doesn’t work, likely a hardware issue. Or, if you have a cable tester, test your in-wall cable.

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Thanks. Will test tomorrow morning to see if power LED goes on when connecting directly from outside.

Seems to me it’s either mice (really can’t imagine this given location) or device failure (also seems surprising - not even particularly bad weather today, so what would cause device to randomly fail I wonder).

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I know we had a few (extremely few, out of almost 100k) devices with failing PoE supplies (not injector - the actual PSU in the router). I believe ZyXEL identified the problem as a batch of one specific possibly bad component. They have a list of affected serial numbers. It's not as simple as anything lower than X. But they'll know.

You should contact them in any case and request an RMA if this is a hardware failure. That's not supposed to happen.

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It's the Zyxel - seems I am super unlucky. Trying the RMA procedure now. Wonder if they'll mind that I put OpenWrt on it.

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Just wondering, could this have been caused by my setup? Do any of these seem problematic to you I wonder(?):

  • somewhat uneven mains power supply, although apparently not uneven enough to warrant the supplier to replace the cable to our house;
  • UPS - APC by Schneider Electric Power-Saving Back-UPS PRO - BR1500GI - Uninterruptible Power Supply 1500VA (AVR, 10 Outlets IEC-C13, USB, Shutdown Software); and
  • PoE - TP-Link TL-POE160S 802.3at/af Gigabit PoE Injector | Non-PoE to PoE Adapter | Supplies PoE (15.4W) or PoE+ (30W).

Could the PoE be over-powered and delivering too much power?

None of my other devices connected to my UPS like my RT3200 or my PC show any problems.

If none of the above, then I suppose I have simply been super unlucky. Device has been totally rock solid, and then just randomly powered off and won't power on.

Actually to my surprise, Amazon UK have indicated that they will simply accept a return and full refund, obviating use of the Zyxel RMA procedure and giving me the full two-year warranty for the replacement product. As a bonus, the price of the NR7101 in the UK has since significantly dropped from £700 to £390. So this cloud has a silver lining.

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I'm no expert, but I don't think it's likely. I assume ZyXEL built in some basic over voltage protection like a zener diode.

Great! Then the problem is solved.

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