turned off unexpectedly and I could only restart it by unplugging the power cord for 5-10 seconds, plugging it back in and pressing the restart button pressed. I first suspected and replaced my APS PSU. But the problem remained. My iMac would shut down in screensaver mode two or three times a day. I have not experienced any disconnections while actively working on the computer. I re-read all the reviews and found others who had this problem. After removing this USB 3.0 hub, the problem disappeared. Search Google for unexplained iMac shutdowns related to USB 3.0. I'm sorry this is happening because this hub looks nice and is very handy for simple USB connections. I also tried this with extra power but same result. You may still find it useful if you can live with the disconnects. It may not affect your iMac, but this is my experience.
iVANKY MacBook Pro Docking Station, 9-in-2 USB C Hub Adapter with 4K Triple Display, 100W PD3.0, Ethernet, 2 HDMI, USB-C 3.0, 2 USB-A 3.0, SD & TF for MacBook Pro/Air
9 Review
UGREEN USB 3.0 Ethernet Adapter Hub with RJ45: Fast Gigabit Ethernet Converter, 3 Ports USB 3.0 Hub Compatible for MacBook, iMac, Surface Pro, Chromebook, Laptop, PC
11 Review
VEMONT 7-Port USB Hub 3.0 with Individual On/Off Switches, LED Light, and 4ft/1.2m Long Cable - USB Splitter Extension for Laptop and PC Computer
9 Review
π uni USB C Hub with Ethernet Adapter, 4K HDMI, Gigabit Ethernet, and 3 USB 3.0 Ports for MacBook Pro, iPad Pro, XPS
11 Review
π USR-TCP232-410s: RS232/RS485 Serial to Ethernet Adapter/IP Device Server with DHCP/DNS Support
4 Review
π CERRXIAN RS232 to Ethernet Serial Device Server - TCP/IP Converter with 1Port DB9 RS232 Serial to Ethernet Connectivity
3 Review
πΆ Netgear Unite AC770S 4G LTE Mobile WiFi Hotspot - Up to 300Mbps Download Speed - Connects up to 10 Devices - Create WLAN Anywhere - 2 MIMO TS-9 External Antenna Connectors - GSM Unlocked - White
8 Review
Smartphone ZTE Blade A7 (2020) 2/32 GB, Dual nano SIM, blue
79 Review