I just downloaded and flashed Version 1-10 (hassos_rpi3-1.10.img.gz), and there is no /system-connections/ folder to set my static IP. (My router is too old to remember IP addresses, with DHCP it changes every time a device is connected).
Do I need to flash again? Should I revert back to Version 1.9? How do I set a static IP in HassIO?
Bobby_Nobble pointed me in the right direction to set the static IP in the router. It never occurred to me that the correct search term was “Static Lease”.