Raspberry Pi 4 Model B (4GB) Wiring Guide/Advice

I also had problems with range at first, but it was because I messed the settings. Try Zero settings shared here:

except that I am using 5.8ghz and UseSTBC=N and UseLDPC=N
By the way, my Ground is Rasberry PI 4 B 8Gb with Tplink T4U plugged to USB 3.0 port directly and all this is powered by simple 3A UBEC connected to Pi via pins.
Air is Raspebbery PI Zero with same card, but at this end everything is soldered, except 3A UBEC is just plugged via pins. GND and 5V goes to card dirrectly from these pins too.
Video was still got at 1.9km range with 6db dipoles on both ends. Didn’t find what is max range yet.

I also noticed this in your description

what is this? If that is hard drive, it might consume lot of energy.