I have installed smart switches before, but I moved into a new apartment recently. I have never had a problem before. I removed my old light switch and installed a new smart wifi light switch, and I lost power to my entire room. (All wall outlets, switches, etc)
The light switch powered up, but did not turn on the light, nor allow me to use anything else in my room. I hooked the ground to ground, hot to black on the switch, load (red wire) to the red wire on the switch, and unbunded the white neutral wired in the back and hooked it to neutral.
I also noticed that fully disconnecting the smart switch and leaving all wires 'safely' exposed, my room did not have its' power restored. I did this to test and see if the switch was bad or my wiring was somehow wrong.
It wasn't until I hooked back up the old light switch and re-bundled the neutral wire that everything started working again.
What is going on here? Is it something to do with the neutral?
Also: I noticed that when the power was on, wires were exposed, but no power was going to the rest of the room, ground-load measured 120v. ground-hot measured 120v. Why was load measuring 120v?
Measuring load-ground when the original switch was working measured 0v with switch off.