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 Ethernet Optics Family Datasheet on https://cloud.kapostcontent.net/pub/a070d154-d6f1-400b-b2f0-3d039ae2f604/data-center-ethernet-optics-data-sheet and to the current SLX-OS20.2.1 for ExtremeRouting SLX 9740 Release Notes .