The two-button light switch does not work correctly

Stanislav asks:

Such a problem. I drove into the apartment, the light in the bathroom was not on at all. The house is old, the wiring is all in the walls, so it is possible to work only with a junction box. I decided to cope on my own, but the maximum I achieved was that the light was on in the bathroom now, but only when it was turned off in the hallway. When I turn it on in the hallway, the bathroom immediately goes out. If you unscrew the light bulb in the hallway, then the phase does not come to the switch. I bought a new switch, the simplest two-key.
Help, please, otherwise this malfunction will drive me crazy !!!

To begin with, if you unscrew the light bulb and the phase does not come to the switch, and at the same time there is NO ONE phase on the wires of the switch, then the switch breaks zero. Disassemble all connections in the junction box, take a dial with long wires and ring all the lines, obviously you have connected the wires incorrectly in it. And if you unscrew the light bulb in the BATHROOM, nothing disappears anywhere?

The phase should come to the switch constantly, and there should be zero on the wire from the lamp (especially easy check if there is an incandescent lamp - just measure the voltage on the wires of the switches, it will be 220V). A phase should come to the switch, and two wires should go, on which there should be phases when the switch is ON. The lamp must be ZERO directly.

Judging by all of you, the situation is as follows:
1. You connected zero to the lamp in the bathroom directly.
2. Zero was applied to the switch.
3. And the phase was applied directly to the lamp in the hallway.

I think that you connected the wires in the box so that zero goes directly to the bathroom, and the second wire from the light bulb in the bathroom is connected to the wire from the light bulb in the hallway, which goes AFTER the switch.

Does the light in the hallway light up when you turn on the light in the bathroom? Well, at least to the floor of the heat somehow? When you unscrew the light bulb in the hallway, does the light continue to work in the bathroom?

And read this article https://samelectrik.ru/elektricheskaya-sxema-podklyucheniya-dvuxklavishnogo-vyklyuchatelya.html. It describes how it should be.