HPE 2920 PoE keeps resetting randomly

[SeattleByte]

I have HP2920 with PoE. It connects several end station with IP desk phones. The total consumption is always below 50W. The main complaint that comes from that department is that the the phones are resetting on their own all at once. Logging reports only loss of power on the port as if it was just unplugged. Uptime timer is not reset. I have occasional Excessive Collisions errors on one port followed by a dozen of STP events (ONLINE-> BLOCKED->OFFLINE) on the same port.

Is that possible that one of the wires gets shorted which causes PoE to be reset on the entire switch?

What can make switch to reset its` entire PoE function without any warnings?

[Vince-Whirlwind]

The other thing that stops power is if the switchport is simply going down and up again.

[TerjeAFK]

I've seen this on HP switches where a computer was connected to the switch through the second data port on the IP telephone and you put them in separate VLANs (tagged for the voice vlan, untagged for the data). Then the switch port would go down and up at regular intervals. Never found a solution for it, so we changed the config so the computers and phones are in the same VLAN.