This scenario describes a physical layer mismatch between the FlashArray optics and the customer's switch infrastructure.
The PER (planning document) specified 10 Gb/s, so the Implementation Engineer likely installed 10 Gb SFP+ transceivers into the array.
The SAN Switch is operating at 40 Gb/s (likely using QSFP+ ports).
You cannot simply "force negotiate" a 10Gb SFP+ optic to run at 40Gb/s, nor can you plug a 10Gb SFP+ directly into a 40Gb QSFP+ port without specific breakout cables or QSA adapters that match the signaling. The physical transceivers themselves are incompatible with the link speed required by the switch.
To resolve this, the Implementation Engineer must replace the transceivers with the appropriate type.
If the switch is 40Gb native, the array needs 40Gb (QSFP+) optics (if supported on that slot).
Alternatively, if the customer intends to use 10Gb, they must provide 10Gb ports on their switch side.
Given the prompt implies the SAN is 40Gb, the 10Gb optics in the array are the incorrect hardware for that link.
=========