SLX 9740 switch routers require QSFP28 optics for 100GbE connectivity, and 40GbE- to-10GbE breakouts for 10GbE connectivity.
For current information about transceivers and cables that is supported by this device, refer to Extreme Optics website and to the current SLX-OS 20.2.1 for ExtremeRouting SLX 9740 Release Notes .