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.
We have found that a macOS client just ping-pongs back and forth between the two ports with no increase in performance. There is an increase in performance with only a macOS server that is connected to multiple clients. To get link aggregation to work, the switch must be capable of supporting it and the two switch ports connected to the Twin 10G must be configured as bonded ports.