Thank you. I updated both drivers which I believed could be the network cards on my desktop, both up to date. I updated both drivers on my laptop, and only one "Realtek PCIe GBE Family Controller" was apparently out of date. I made a file transfer test at every change, and after updating this driver, it went to 80 MB/s (most of the time).
Now, I also tried over WiFi this time, and, while there was a small improvement, the speed is still too low, just 15 MB/s, and the wireless driver is up to date.
These are screenshots from the laptop:
There is the wireless adapter, "Qualcomm Atheros"
The speed I get after updating all drivers, and doing the things you recommended, setting "Speed & Duplex" to "1.0 Gbps Full Duplex" and all possible network adapters (both on the desktop and the Realtek on the laptop), and also disabled the "Large Send Offload v2 (IPv4)" on all possible network adapters.
But, the wireless adapter doesn't have any of those options there, so I made no changes.
Now, I went to the manufacturer's site and tried to look for the drivers. The computer came with Linux I believe, and I remember having trouble with the graphic drivers, I had to remove the updates and not update it never cause most games wont work (15 fps on Sekiro, others would just be a blank screen, etc.). So, maybe I need to uninstall the Wireless driver and install the first version available? But there are 2 options, and I'm not sure which one to use
Or maybe I need to do something else to improve file transfering speed over WiFi, any ideas?
EDIT: Also tried using right now a USB WiFi adapter with 450 Mbps, this one, also installed the latest drivers from the manufacturer's site and also tried to update with windows update, and it was up to date. Made a test and I got 12 MB/s. Is this normal for wireless file transfer or am I missing something? My router can transfer at 1300 Mbps. And yes, I made sure to use "WiFi 2" using the new adaptor, and disconnected with my integrated wireless adaptor.
TL;DR: Integrated wireless adapter = 15 MB/s , USB WiFi = 12 MB/s