HELP! Wiring Leviton DZ6HD with a DD00R

I cant seem to figure this out. I have a switch upstairs, a switch by the garage, and a switch by the back door (is this a 3way or 4way? I rarely use the switch by the back door and my old setup, lutron maestro, was hooked up fine at the backdoor and upstairs). Anyways, Here is the layout. I am not sure which one gets the main wires from the electrical box. But after following some wires, i know the backdoor wires go to the garage door box. Any help is appreciated, I am going on 3 days trying to figure this out. (I kind of know which wires are the load and line, not 100% sure. Right now i have the lights working from the DZ6HD but cant be turned off by the DD00R or vice versa.

North America called it 4 ways. 3 switches and a load. By the look of the number of romex. It does not look good. High chance the romex from your breaker is going to your light fixture box. This means you won’t have a neutral wire at any of your box. You need to use a volt meter and figure out your wiring configuration first. Here’s a site with 2 common 4 ways. There are a couple of other 4 ways but they are not common.

When you say I don’t have any neutral wires, I am confused. There are white wires in all the boxes and they power the switches. I don’t really need the switch by the back door, can I get rid of it and just make it a 3 way?

I am just guessing base on your drawing above. With 3 and 4 ways wiring. White could be anything so don’t rely on wire colors. Only way to figure it out is by measuring. A neutral wire is a white wire connecting to a neutral bus from your breaker panel and usually in the same romex as the line hot wire. Any white wire not connecting to the neutral white wire is not a neutral wire.

All the white wires are connected to each other. I took a couple pics with the switches removed. The first picture is upstairs and the second picture is the garage door. The other switch is still hooked up to 3 way switch as labeled on the pic in my first post. I also think the switch starts at the stairs from the electrical box. I am going to go into the attic and check.

(The one white and black wires with an orange nut are not part of the lights. They are from an outlet that was next to the light switch)

Garage door switch

The pictures don’t match with your drawing and now it does make a little more clear. I see 3 romex cables going into the 4 ways switch. Also it looks like you do have line and neutral. Can you confirm the wires from the outlet beside the switch are also connecting to the switch? Possible you could take pictures with the switches with all the wires still in place especially the Common terminals?
How did you connect the Leviton switches?

the outlet besides the switch is on a separate breaker (I have 2 breaker panels in my basement, the house is from the 1950’s and they upgraded some of the electrical).

I took some pics and i also put back a regular 3 way switch and it works fine except the switch by the backdoor doesnt work which is fine by me.

first two pics are from the upstairs, you can see there is power to the one black wire (BLUE TAPE) that comes in from the top (No traveler wire in that bundle). is this the load?

the other one has no power.

the second set of pics (blue wall) is the garage door entrance. no power on any wire with the breaker on.

now the way i had it wired turned on the light but not a 3 way. this is how i had it.
(this is upstairs again, only wire on the other side is the white wire)

Then garage entrance again

That’s your Line hot. Load is a wire from your light bulb so with everything disconnected the wire with power is your Line Hot. The load wire is the wire with power when the light bulb lights up. You won’t be able to know your load with everything disconnected.
No chance you could get a volt meter? looks like the 2/14 romex is coming from your light fixture with the black wire is your Line hot and the white wire is your Load with the red connector going to your 4 ways connector with other white wires then to the back door white. I see you added white pigtail thinking they are neutral.
you can check the neutral with a volt meter by placing one probe on the Line hot wire and the other probe on the white wire on the same romex. you should get voltage and No voltage when you remove the light bulb.
If you don’t have a volt meter. with the switches connected. place your volt detector on the white wire and turn on the light. If you see voltage or not? if you see voltage then remove your light bulb and see if you still can control the switch and check voltage of the white wire. If you can’t control the switch then the neutral is at your light fixture and you are getting through the bulb.

wow, is that normal for them to have a white wire as the line?I might have to get a buddy who knows this stuff to label everything before I can try this again. I ve spent over 15 hours trying to get this to work and i lost my patience last weekend. I do have a multi meter (not an expert on using it though).

I actually had a GE 12724 and a GE add on switch hooked up before and it worked except when i turned the living room lights on/off, the lights downstairs would go off then come right back on. Drove me crazy, but now I put them back and was going to try and pair the two GE switched with a minimote and see if that took care of the problem. Maybe thats why its doing that, its because one of the white wires is not what it seems. I am going to have to go back to the drawing board and get everything labeled, i tried so many combinations that I dont even remember any of them. :unamused:

PS- It kind of sucks this forum limits my posting. I had more pics to show but was cut off because i am a new member, and that just added to my frustration.