NanoPi R4S

https://wiki.stoplagging.com/books/technical-guides/page/sqm-for-1-gbps-lines-with-openwrt

Refer to the link above for the full tutorial to the NanoPi R4S method. It is the most cost efficient method for loads higher than 300Mbps. It can handle SQM with 1Gbps no problem! This is also what I currently use at home for a 800 Mbps connection.

The NanoPi R4S is a cute small 2-Ethernet port 6-core ARM 1GB RAM machine. For $100 it is very cost-effective for the performance given. You will need to pair this with a Access Point for WiFi capabilities and buy a gigabit switch if you need additional Ethernet ports.

It runs FriendlyWrt, a version of OpenWrt, off a MicroSD card.
P.S. I may have one extra for sale if you need one. You usually have to get it from a comapny called friendlyElec which has a long lead time of 4-5 weeks.