Operating System Requirements: macOS X 10.8-macOS 10.12 Description: This is a unified driver for all Twin10G models and Presto 10GbE dual-port (Intel) PCIe cards for Mac computers with macOS 10.8-10.12
To install under High Sierra:
1) In System Preferences...Security & Privacy panel...General tab...under "Allow apps downloaded from", select "App Store and identified developers".
2) Download and install this driver and follow the on-screen instruction.
3) If the driver doesn't load after a restart, you may need to go to System Preferences...Security & Privacy panel...General tab, and manually authorize the Sonnet driver and restart.
No, you cannot. The Twin 10G supports connecting to only one computer. You may connect only another Thunderbolt peripheral to the second Thunderbolt port of the Twin10G.
