Ethernet with PoE and onboard SD card

Hi, i might be overlooking something really obvious and i will be grateful to anyone pointing me in the right direction - the question i am looking to answer is - is there a straightforward way to equip an Arduino board with Arduino Ethernet Shield PoE capable?

i am seeing a lot of work-around scenarios proposed online but no straight scenario to build this. a number of Ethernet Shields PoE capable seem to be retired - is there a plan forward for a replacement?

i am looking to build a simple scenario where an Arduino board can be powered with PoE Ethernet cable connected to PoE switch and communicating over IP network.

another ambiguous statement in the Arduino Ethernet Shield specs page - "Note that because the W5100 and SD card share the SPI bus, only one can be active at a time" - what exactly is "one-at-a-time" referring to? one per loop or does that mean if one is enabled the other should be completely disabled?

a simple scenario i can imaging is storing records on the SD as a temp caching mechanism to store data during periods of IP connectivity loss - so the data could be picked up and transmitted later when connectivity is back - is this something that would be possible with SD on board the Ethernet Shield?

thanks to all taking to contribute. any clever thought are much appreciated.

another ambiguous statement in the Arduino Ethernet Shield specs page - "Note that because the W5100 and SD card share the SPI bus, only one can be active at a time" - what exactly is "one-at-a-time" referring to? one per loop or does that mean if one is enabled the other should be completely disabled?

It means that the Arduino can talk to/listen to the W5100 OR talk to/listen to the SD card, at any given point in time. It can read some data from the SD card, then write that data to the W5100, then read some more data from the SD card, write that data to the W5100, and on and on.

Or, it can read from the W5100, then write to the SD card, and repeat until all the data from the W5100 has been saved to the SD card.

The SD library and the Ethernet library each properly manage the SPI bus - disabling all passengers, enabling only the intended passenger, dealing with that passenger, and then enabling all passengers again.

Your code doesn't have to do anything more than use the two libraries properly.

Personally, I can't understand the need for POE. If the ethernet cable has power, there is power available somewhere, not that far away, that can be tapped to power the Arduino.

"Personally, I can't understand the need for POE. If the ethernet cable has power, there is power available somewhere, not that far away, that can be tapped to power the Arduino."

So can you tell me where to buy a 10-meter AC / DC adapter, please ?
If wifi is not desired, an RJ45 cable can easily power the POE.
Tested and approved.