Make sure you turn off "smart setup" on the Smarthub.
See link how to do that.
Some devices including Apple devices have a problem with the Smarthub dual band having the same SSid (name). You should try splitting them.
Are you sure you are performing a full factory reset. You need to hold the reset button in for at least 20 seconds. If you don't do that all it does is a "soft" reset.
You would appear to be doing it correctly. I was just checking because it should reset everything including your password, smart set up etc.
To be honest I've not been impressed with iSO12 holding any type of connection. If the hub reset has not helped, you could try turning off wifi calling and see if this makes any difference.. make sure you make a note of any wifi network passwords before doing a network reset.