@TZR209 

Sorry, the 160Mhz was my mistake. It is on an AX router and I think they are the only ones what can do that, and it i s one of the key features of Wi-Fi 6 (802.11ax) standard.

A fairly cheap AX20 still will only connect on 5Ghz at 1200Mbps... Higher end ones might do better, but if you want to get max. speed, you'll need to get an AX router that matches all the capabilities of the wireless card.

Thanks everyone. I chatted with TPLink customer svc last night, they say the C8 has 80mhz channel width (auto), and the A20 has 160hmz channel width (auto).

-So If the C8 is 3x3, the client adapter is 2x2, the link speed is 886.7, what is the channel width? 80mhz?

-And the A20 is also 3x3, the client adapter is still 2x2, assuming the channel width is 160mhz, what is the best possible link speed?

NOTE: According to Intel, this 2x2 adapter can do 1733mbps link @160mhz channel width. But the A20 specs say 802.11ac 5GHz link speed is 1625Mbps (seems to be an odd number).

I did an online chat with TP Link and they also said the A20 can do 160MHz width. So I purchased an A20 and did NOT get 160MHz channel width, still stuck at 886.7Mbps. In addition the A20's max speed on 5GHz AC band as reported by Acrylic Wifi is 1300Mbps, same as the C8! Despite TP Link advertising 1650Mbps (which is an odd number). Ended up returning the A20 for a refund, and won't be trusting information provided by TP Link chat or advertising or vague specifications.

After reading:

https://www.smallnetbuilder.com/wireless/wireless-features/33210-160-mhz-wi-fi-channels-friend-or-foe

I purchased a Netgear R7800, enabled HT160, choose a DFS channel, and instantly got 160MHz channel width as reported by Acrylic Wifi. And my AC9560 link speed is now showing 1.7Gbps. Huge increase in file transfer rates to (wired) LAN machine, and internet speed test (with 1Gb xfinity) to this machine is now more than 800Mbps (same as wired machines through switch+router). So far no negative effects.