Minecraft – Nether Portals not linking 1.16.4

The coordinates aren't lining up. You should rebuild your nether-side portal 11 blocks further north at z=-6.

As you said it yourself, portals do take the vertical distance into account. This means you cannot make a sky portal higher than y~=192 if your ground portal is at sea level, as distance from Nether ceiling (your top portal) to sky portal must be less than from Neither ceiling to level of your ground entrance portal.

  Overworld|Nether

Sky    [@]                          192
           ^
          A|
           v
             [@] Nether top         128
             [@] Nether bottom
           ^
          B|
           v
Ground [@]                           64

But there is a solution!

By moving your ground entrance away horizontally, you can increase distances just enough to fix all the portals (after moving Nether portals to the ceiling, of course).

I have written this handy spreadsheet to easily calculate all distances for two pairs of portals (coordinates in frames are editable). By just moving ground portal from x=-3653 to x=-3623, thirty meters away, you can fix everything! Well, maybe a couple meters more to be sure :-) Again, note I've assumed your Nether portals to be at y=110 and 120, otherwise your Ground portal would have to be much farther.