What 6E adds to Wi-Fi 6
Wi-Fi 6 is the 802.11ax standard, and the Wi-Fi Alliance began certifying devices in September 2019. Its main features are OFDMA, which splits a channel so several devices share one transmission, MU-MIMO, target wake time for battery life and 1024-QAM, which packs 10 bits into each symbol.
Wi-Fi 6E is the same technology on a new band. The Alliance started certifying it on January 7, 2021, after the US FCC opened 1200 MHz of 6 GHz spectrum to Wi-Fi. That space fits up to seven 160 MHz channels, and they come without the Dynamic Frequency Selection restrictions of 5 GHz. Only 6E and Wi-Fi 7 devices can use the band, so older phones and laptops stay off it. The Alliance also requires WPA3 security for 6E.
The cost is a little range. On average a 6 GHz signal loses about 2 dB more than 5 GHz in the first meter, and Extreme Networks says that gap won't be a serious concern in most indoor networks.
Where 2.4 and 9.6 Gbps come from
The top figure for 802.11ax is 9.6 Gbps, which means 8 spatial streams at 160 MHz and 1024-QAM. Each stream is 1201 Mbps. Most devices you own have one or two streams. Intel's AX210 laptop card, for example, has two streams and 160 MHz channels, and Intel rates it at 2.4 Gbps.
In file terms, 2.4 Gbps is 300 MB/s and 9.6 Gbps is 1.2 GB/s. Those are link rates, the speed the radios signal at, and they're not what a copy sees.
From link rate to file speed
Wi-Fi is a half duplex medium with management overhead, in Cisco's words. Only one device talks on a channel at a time, and the acknowledgments, beacons and gaps between frames use airtime that carries no file data. Cisco's guidance is that a good test shows about 65% to 70% of the rate the client reports.
On a 2.4 Gbps link that's 195 MB to 210 MB each second, and that's with one client. Cisco warns that using several clients divides the result and increases collisions, so a busy home or office network gets a share of that. Weak signal pushes the link rate itself down.
So plan around the rate your device negotiates, and take off a third before you compare it with a wired connection. The 100 GB over WiFi 6 page works the copy time out for you.
When 6E is worth it
6E helps most where 5 GHz is crowded, like apartments and offices, since 6 GHz is free of older devices. It needs a router with a 6 GHz radio and clients that have one. A 6E router adds nothing for a phone that only supports Wi-Fi 6.
If you already have a Wi-Fi 6 router and a mix of older devices, the gain can be small. If you're buying a new router and keeping it for years, a model with 6 GHz leaves room for Wi-Fi 7 clients, which also use the band.