Different Wi-fi up/down speeds from different sources, where to look?

Question

Computer networks

There are 4 devices on the same local network. 1 - improvised nas (banana PI running a knee version of ubuntu armbian) 2 - laptop 3 - desktop computer. 0 is a black box router, everything passes through it. Case 1 - all devices are connected to the network by gigabit wires, everything is fine - all have a download speed from NASA of 35-45MB / s in both directions. Case two - the laptop is connected via 866-1.7Gb Wi-Fi. The laptop downloads from NASA - 6-10MB, uploads - 30-35MB (it can't be faster than us), from the hospital - 70-80MB (nvme disks) in both directions.
The problem is, as you might guess, downloading from us to a laptop via Wi-Fi. Before that, the upload was as bad as the download (5-10MB), but it was cured by commenting the line "socket options = TCP_NODELAY IPTOS_LOWDELAY SO_RCVBUF=65536 SO_SNDBUF=65536" in the samba config. Indications are not only downloading files, but also iperf3 says the same thing - 300+Mbps upload ON us, 60-80Mbps down C us-a. Perhaps somewhere in the "optimizations" of traffic on the side of us. Or maybe not where to dig, if all the configs are basically default, yesterday I went through everything and didn’t find any extra lines. MTU us 1500, laptop 1500, router 1500, computer 9000.
What could be the reason? What can be twisted, what can be cured, where to dig?

Answer 1

Are you sure the problem is software and not technical? for example, a weak network adapter on a laptop