[throwaway189262]

Linksys WRT 3200 and Netgear R7800 are the fastest popular OpenWrt routers. You want a popular ones because they are usually least broken and easiest to flash. Be warned, some routers have broken 5ghz and other issues. Make sure to check the OpenWrt device page before buying. I have seen forum posts that these routers can handle 300 megabits+ but not sure about 1gig

Your best bet for such speeds is running on X86. OpenWrt runs fine on regular desktop PC if you use hardware with good Linux support. Especially be cautious of the wifi drivers/device. Or, you can traffic shape with the PC using two gigabit NIC's and leave the wireless to a "dumb AP" regular router.

So yeah for one gig shaping I think the best option is a regular X86 machine with good NIC's (Intel maybe). You can get fanless ones sold for home theatre. Or, what I recommend, use a regular PC in a cheapo case with Noctua A Series fans. Even at max speed Noctua A fans are barely audible. And you can turn them down in BIOS if you get a decent mobo

You can try it with an old machine first but make sure it at least has PCI Express. Old school PCI slots only have 1gig of bandwidth so having two (one lan, one wan) will max out the bus. My first gen core i5 750 was able to shape at 400 megabits with the bus maxed out :)

I'll add to this, to get holy grail per-ip balancing with SQM CAKE you need to enable an advanced option. See https://openwrt.org/docs/guide-user/network/traffic-shaping/... section "To enable Per-Host Isolation"