Hello there! 😁😁😁
Looking at your screenshots attached there are some settings that definitely need to be revisited.
As many have indicated the bitrate should not be set from the minimum all the way to the maximum, as it doesn't benefit your network allowing any device to connect at very low MCS Rates.
We generally indicate to use 11Mpbs minimum if you require 2.4Ghz or 12Mbps if you do not.
Your transmit power is also set all the way to the maximum ↗️, this is not recommended, you should find the right range 🚥 and configure it accordingly.
A site survey 🔎 should be done to understand what is the minimum ↙️ and maximum ↗️ dBm you should configure so your AP doesn't start causing interference with others.
Being under the AP is also not good, the AP transmits its best signal horizontally ⬅️➡️ and then vertically ⬆️ (upwards mostly and a little bit downwards), you can see the isotropic graph on the last page of the PDF manual 📖.
Being too close to the AP can be almost as bad as being too far, if the signal comes in too strong 💪, it will be the equivalent at being at a rock concert next to the big speaker 📢, your signal will not be clear causing all sorts of strange behaviours.
This website http://mcsindex.com/ has some really cool information ℹ️ on what the requirement are in terms of modulation, coding and spatial streams to achieve the desired speed 🚤.
Once you have everything reconfigured you are then at your best ideal state, then you need to start taking into account, noise, interference from neighbouring APs, number of clients connected, number of SSIDs, the more connections you have, the more overhead you will have, this will all greatly affect the speed that you connect to the Cisco Meraki AP.
To just clarify, this is not specific to Cisco Meraki this is how it works on any and every vendor.
Let us know if you need any further help or guidance.
Cheers! 👍
