The WRT1200AC family is not well supported. The Ethernet part should work fine, but the Wifi is unsupported since some years now, see here the repository: https://github.com/kaloz/mwlwifi The vendors are not interested in this hardware any more, but they have very good marketing and sales. Linksys and Marvell also did not really support the OpenWrt community, they just had good marketing. If your WRT1200AC device does not work well with OpenWrt do not complain to OpenWrt, but complain to the Linksys support.

The WRT1200AC family for example does not support WPA3, because the closed source Wifi firmware does not support it. The 15 years old WRT54G supports WPA3, it is just very slow. ;-)

Currently I would suggest the Linksys E8450 / Belkin RT3200 (same hardware) or some other device using the current Mediatek platform with MT7622 + MT7915 + MT7531. (2 X Cortex-A53, Wifi 6) All chips are supported in recent upstream Linux kernel, including Wifi. The Mediatek router team is currently doing pretty good upstream open source work for their chips.