This has probably been asked before. In order for the switches to operate, both must be "on." this is fine, except when someone walks into the bedroom then turns off the hall light, the next person, cannot turn on the hall light at the beginning of the hallway. I've looked through posts, but haven been able to find this one.

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    If that's true then someone miswired them. – Carl Witthoft Apr 29 at 17:59
  • Can you post photos of the insides of the boxes involved please? – ThreePhaseEel Apr 29 at 23:46

That's not how 3-way switches work. This is how they work.

enter image description here

Now you see, there are two travelers. One is hot, and one is not.

The act of throwing a 3-way (or 4-way) switch exchanges which one is hot and which is not. The very last 3-way chooses which one to rely on. If it's on the hot one, the lamp lights.

And by the way, I recommend you get colored tape and remark all your in-box wires with exactly these colors. That way, instead of looking at Egyptian spaghetti (black red white gold), you go "Two yellows! I know what those are!" A wire remarked red! I know what that is!

Now, if this scheme does not work for you, you might be trying to pull it off with the wrong cables. You need, as a minimum, /3+ground cable between the switches. (and sometimes you need more wires, and must go to smurf tube and THHN because cables with that many wires aren't readily available. You cannot gang 2 cables.)

And if this places you at an impasse, you now have a Hail Mary play available: the smart switch. Smart switches can often give more functionality out of fewer wires.

We see it from time to time where someone installs /2 cable between switches, and either abuses the bare wire, or sources neutral from the other box. These are bad installations that should be removed at once. Smart switches are the best way to resolve that.

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