I decided to replace my quite old Netgear switch to something modern, which would also support PoE, so that I can remove one or two power cables.
First I tested it in isolation with the Mikrotik cAP-ax access point and it worked well: no power adapter needed.
After replacing the old switch with the new one GS308EP I discovered that my another devices Mikrotik hAp-ac2 is not responding and the wifi is not available anymore.
I tried several options to recover it:
restarted
made a hardware reset
uploaded a new bootloader using netinstall (both Router OS 7 and 6)
But still nothing: rebooting and attaching ethernet cable to any of the 2-5 ports with configured 192.168.88.2 IP address is not able to ping 192.168.88.1. The Miktotik wifi network is not appearing as well. But the ethernet link is up somehow.
The official page (and port 1 itself) says it supports PoE, so I would not say I did something wrong.
Is it possible that I bricked my access point?
Is there anything else I can do to recover it?
Well, hAp-ac2 supports passive PoE 18-28V. (and it uses Mode B aka positive on pins 4 and 5 and DC negative on 7 and 8 and data on 1-2 and 3-6)
Cap Ax supports 802.3af/at 18-57 V.
The GS308EP supports 802.3at.
That the cap Ax worked is normal.
But the 802.3af and at protocols include some “probing” for what is connected to a PoE out port and if some negotiation do not succeed the PoE out device should NOT supply the 48V voltage, i.e. the hap ac2 connected to a PoE out source should have not powered at all.
Cannot say if you can on the Netgear “force” the PoE out, but if it is possible and you did it, your hap ac2 may have received a survoltage, but on which port was the PoE applied to?
Still if you could reset/netinstall it the device still works/boots.
The Netgear GS308EP had factory defaults and I disabled PoE on all other ports right after discovering the problem. I don’t remember it had “force” or similar mode.
I think the default was 802.3at and power limit 30w.
The Mikrotik hAp-ac2 was connected to the switch using port #1 (which supports PoE). All other ports were not used.
Still if you could reset/netinstall it the device still works/boots.
That’s sounds optimistic, but I wonder why I’m not able to connect..? Also, missing WiFi network might be a sign of a problem.
It feels like there was some short circuit. But I’m not sure if that would have symptoms like I currently describe.
If the device boots/netinstalls/etc. it fundamentally “works”.
It is entirely possible that a part of it is “fried”, but if for whatever reasons you applied an excessive voltage to ether1 I would expect It to fry, not the other ports.
The 802.3 af or at negotiations are designed to prevent that, so it should not happen, and - logically - if against all odds It actually happens, It should happen on the part of the board that received the shock.
It is (IMHO) highly improbable, if connecting by mistake a 802.3af/at PoE out to an ethernet port of another device (passive PoE in or not PoE at all) could result in a fried device we would have seen tens or hundreds of similar reports, but of course you never know.
I don’t know how this has happened, but today in the morning I decided to try WinBox and it found it – with 0.0.0.0 IP address!
And all the configuration erased, e.g. wireless networks disabled. This was quite a surprise for me: I though after netinstall it would have factory defaults, not the empty configuration.
The official documentation mentions:
After using Netinstall the device will be reset to defaults (unless you specified not to apply default configuration).
but I did not specify anything special.
Anyway, after discovering and connecting to AP I did proper hard reset and all the setting now were back to factory defaults.
I quite happy that on this Friday 13 my router came back to life
Thanks everyone!!
