It is indeed a shielding, resp. grounding issue.

Any outdoor AP must be grounded in order to mitigate against ESD. Proper grounding/shielding is extremely important for outdoor APs. They are exposed to electrostatic discharge in the atmosphere, which can cause voltage shifts incorrectly interpreted as reset signals. See the installation guide, it explicitly mentions the need for proper grounding.

Sorry , we are experiencing the same issue the last two weeks, after more than six months with no problems at all. The AP was not connected to ground (where the antenna is placed there is no gnd access closer) but it has been working fine just for the last two weeks as I said. I have replaced the AP with a new one but the problem persists. We have changed the entire UTP cable and POE inyector with no success. Are you shure it's not a firmware bug...?

Gerardo-ARG wrote

We have changed the entire UTP cable and POE inyector with no success. Are you shure it's not a firmware bug...?

UTP cable is not recommended. Use at least F/UTP, S/UTP or even better SF/UTP (formerly known as FTP, STP and S/FTP) cable. Grounding can be realized through the cable if the antenna pole has no grounding capability, so use proper outdoor cable with an additional ground wire (e.g. UBNT ToughCable). I have lot of CPEs/WBSs in the field and never ever experienced factory resets out of the blue, not even once. So I doubt that it is the firmware, but can't rule it out either that probably newer hardware versions of CPEs might be more sensitive to voltage fluctuations (rather than a bug in the firmware).

Anyway, only way to find out is to fulfill the basic requirements for an outdoor setup described in the installation guide, first sentence (grounding) and second sentence (shielding) here:

If you ignore grounding requirements, problems will occur sooner or later, which can be anything from sporadic instabilities up to a total freeze of the device. That's not specific to Pharos devices, but to any outdoor device exposed to atmospheric discharges caused by storms and lightning.

I understand! But my mistake: The reset it's only at power level, configuration is not reverted to the factory one, BUT after startup when I go to web interface I find an advertisement asking to save recent changes we have made (???) We are using external UTP cable, and this reset its present only in one of our three wireless connections (one of the other two has the same equipment [CPE510] but not upgraded to the last firmware version, its running for about 170 days since the last reboot and the third one is using Ubiquiti NanoLocoM5 for at least 30 days after the last reboot).

Why if I've changed all I'm still having this issue, even the other side connection has no reset/reboot problems (client mode, same fimrware version)

BUILD 1                                                                                                                                                         BUILD2

LAN1 ----- CPE510 in AP mode firmware v2.1.6_170908 (THIS IS the one it reboot itself) -> 100 meters <-CPE510 in CLIENT mode v.2.1.6_170908 ---- LAN2

In another corner of the rooftop we have the same topology with both CPE510 (but running old firmware) and the Ubiquiti third wireless link.

Gerardo-ARG wrote

I understand! But my mistake: The reset it's only at power level, configuration is not reverted to the factory one, BUT after startup when I go to web interface I find an advertisement asking to save recent changes we have made (???)

The remote reset works by pulling one of the + PoE lines to GND (IIRC). A short activation just resets the device, while holding it down for more than 7 sec. resets it to factory defaults. The message about saving changes might be caused by values changing during normal operation such as DFS radar detection count or other log data, it happens all the time. I have not investigated further, since it doesn't change operation of the device if such changes are not saved. In my experience this does not affect the setup in any way, so I don't care about this message (albeit I would prefer to not see it any time I log in).

Why if I've changed all I'm still having this issue, even the other side connection has no reset/reboot problems (client mode, same fimrware version)

This might happen due to humidity inside the connectors, crosstalks of lines or voltage drops of the PoE adapter resp. an instable power supply. Did you exchange the PoE adapters also or only the CPEs and the cabling? I would give a shielded cable a try. You could use any shielded patch cable to test and if it helps, replace it by an outdoor cable later.

Ok!  I've understand now how it works the reset/reboot/reset-to-factory!  On friday we have replaced the ground cable and simoultaneously the external UTP cable for a new one, we have moved the PoE inyector to a more closer location and, so far, we have no new reboots on the CPE.

Thanks a lot for all your support guys!