Allied Telesis AT-MCF2012LC/1 - Manual (Page 21)

AT-MCF2012LC and AT-MCF2012LC/1 Media Converter Modules Installation Guide
21
The auto-MDI/MDI-X feature is only available when a
twisted pair port is using Auto-Negotiation, the default
setting. If you disable Auto-Negotiation and set the port
speed and duplex mode manually, this feature is disabled
as well and the port defaults to the MDI-X setting. This may
require the manual configuration of the MDI/MDI-X setting
on the port or the use a crossover cable, depending on the
wiring configuration of the networking device connected to
the twisted pair port on the module.