Start here with what you can expect, before ISP line/switch/Ap-model considerations come into play: https://mcindex.com/
which is the theoretical WI-FI speed, expect 50% of this.
(Find your favorite Ap's maximum values in a horizontal axis, and a client device connection mode in the vertical)
and of course as in the previous post, the lowest common multiple of ISP speed, to ~90%, i.e. of the 300 Mbs, > 270 Mbs. Which means that you need at least 1 Gbs, on all connected devices [~10 Gb on central one > LAN], and corresponding transaction capacities in other infrastructure to process this in the number of clients to be served, and always allow JUMBO frames [9k]. Then the client/AP equipment capacities in relation to the MCS table will give you theoretical/practical speed capacities and user satisfaction.
Do not exaggerate the AP load beyond the SSID default of 64 clients, if the latest and greatest APs are not used, consider lowering it, and increasing the number of APs, in crowded areas, and look over the number of SSIDs, and look over the bandwidth (20/40/80/160Mhz) settings..Good luck
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Steinar
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