The Koogeek "smart" power strip is a nice HomeKit accessory, but it appears to be discontinued. If you need to change its wi-fi setting, good luck. The user manual is 404 on the company's website.
After much gnashing of teeth, here's the secret:
1. Before we begin, remove the accessory from your home using the Home app, Holmes.
2. Hold down the on/off switch for Outlet #1 for 10ish seconds, until all the other lights go off and the light for Outlet #1 flashes slowly (mine is green)
Then you can use the Home app to add it to your HomeKit network.
Hint: Outlet #1 is closest to the power cord.