I am testing the actual speed of transferring a file from a network share.
Over my 1 Gigabit Ethernet I get about 120 MB/s - that's 96% of the theoretical maximum.
Over my old Wireless G I get about 2.5 MB/s - that's only 37% of the theoretical maximum of 54 Mbit/s.
Over my new Wireless AC I get about 30 MB/s - that's only 28% of the theoretical maximum of 866 Mbit/s.
The client and server machines are the same in each case. They have huge amount of CPU power and a nice array of M.2 NVMe SSDs, so the hardware should not be an issue.
In both cases the high-level protocols are the same, so the protocol overhead should be the same (except the physical layer). SMB -> TCP -> IP -> PHY.
For the wireless case the client and server are put about 1 m apart, in line of sight and in a rural area with no or little traffic over 2.4 and 5 GHz.
Why all my wireless connections are so far away from the theoretical maximum compared to Ethernet?
(Using ASUS RT-AC88U for the Wireless AC test).