Some context here: this is for Belkin / Linksys WRT1900AC, which was released as a premium open-source router, with OpenWRT support, now close to about a year ago…

Except it actually wasn’t open-source and didn't have OpenWRT support, due to the missing WiFi drivers from Marvell…

https://forum.openwrt.org/viewtopic.php?pid=230686