Our company bought 3 cAP Access Points, and two of them stoped working after being configured (only disconected from the electricity, and reconected after one day). AP still broadcast SSID but ethernet socket get up for 3 - 4 seconds and goes gown. I did factory reset but it didn’t help. The third AP didn’t work from the beginning, and was send under warranty to service. They told that it was overvoltage. How cen it be, when i only plugged it to PoE switch, wich powers other devices (one of them is Mikrotik router) and nothing happens to them. It is possible that other two are also overvoltage. What else can i do to with these two AP?
Specifications of cAP are that it accepts supply voltage up to 57V. Which is the same as 802.3 af/at/bt specification. However it is possible that your PoE switch supplies slightly higher voltage which then trips cAP (e.g. 58V). With longer UTP cables there’s some voltage drop and even with slightly too high supply voltage things may work whereas short cables break things.
However, your statement “AP still broadcast SSID but ethernet socket get up for 3 - 4 seconds and goes gown” indicates a different problem (if it was PoE problem, entire cAP would reboot). Which could be almost anything, including xSTP problems. I suggest you to connect to cAP (even via wireless if that connection is any more stable) and check logs (/log print) to see if there’s some better information about what’s going on …
Edit.
Somehow i was able to get into the AP over www by phone (after another factory reset) and check logs. There was only one thing that’s worry me - it connect to switch over 10Mb/s full duplex (switch is 100Mb/s). When i switch ip address from brige to ether1, it was able to respond to ping but, no winbox visibility (deleted any firewall rules) or www over ether1.
Second AP, after factory reset, is dead. Power led is on, but wifi restarting every few seconds, and ether1 isn’t connecting at all.