Allied Telesis AT 8000/8POE - Manual (Page 66)

Chapter 4: Port Configuration
66 Section I: Using the Menus Interface
connecting an end node with a fixed duplex mode of
full-duplex to a switch port, disable Auto-Negotiation
on the port and set the port’s speed and duplex mode
manually.
 The only valid setting for an SFP port is Auto-
Negotiation.