Unwrapping for a lightmap just doesnt work

Hey, maybe someone can help me out with this

I have this simple window:


The automatically generated Lightmap causes artifacts and changing the resolution doesnt change that so I tried to figure out a way to unwrap this in a way that eleminates such.
Now, no matter what I try, there always are artifacts created in the weirdest ways like:

In this example I tried to use project from view in blender to just figure out if its possible to have one side look okay without any lightbleeding artifacts, meaning my lightmap UV looked like this:


Now, the resulting build model looked like this:

The part that I now dont understand, the left bottom windows bottom face seems to be the only thing within this model, that seems to be fine after building lights, yet if you look on the lightmap from before- this model is symmetrical and the face that turned out fine on the left is unrwapped the same way on the right, yet this one turns out completely different.

I really want to know why, but even more Id like to know how I could unwrap this in a way that would finally work for this window.
Id really appreciate any type of help with this one

you can not duplicate or have overlapping uvs. that doesn’t work.

have you tried to use the actual lightmap pack unwrap in blender? that should get that done. make sure the margin fits your targetted lightmap resolution settings or it will bleed across different faces.