Hello,
is this maybe your problem?
Auto-MDIX is supported on all 10/100 and 10/100/1000 Mb/s interfaces. It is not supported on 1000BASE-SX or -LX small form-factor pluggable (SFP) module interfaces.
--Some more informations:
Usage Guidelines
When you enable auto-MDIX on an interface, you must also set the interface speed and duplex to auto so that the feature operates correctly.
When auto-MDIX (and autonegotiation of speed and duplex) is enabled on one or both of connected interfaces, link up occurs, even if the cable type (straight-through or crossover) is incorrect.
Configuring Auto-MDIX on an Interface
When automatic medium-dependent interface crossover (auto-MDIX) is enabled on an interface, the interface automatically detects the required cable connection type (straight through or crossover) and configures the connection appropriately. When connecting switches without the auto-MDIX feature, you must use straight-through cables to connect to devices such as servers, workstations, or routers and crossover cables to connect to other switches or repeaters. With auto-MDIX enabled, you can use either type of cable to connect to other devices, and the interface automatically corrects for any incorrect cabling. For more information about cabling requirements, see the hardware installation guide.
best regards
Sebastian
