That's new (on n0001) :
PXE-E61 Media Test Failure, Check Cable
… and PXE boot aborted. Checked cables → probably not the problem. Moved them to new ports → it booted. Went to the switch and, voila, the respective ports on the switch had been downgraded to 100 and 10T. Forced them both to 100T, imposed flow control, and this time the node booted.
⇒ No : still problems. Take it down for now. Is it the switch ? Is it permanent ? We'll have to wait till the next power failure …
⇒ Next day came back to normal. ???