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.
You usually have to get it from a company called friendlyElec or from aliexpress which has a long lead time of 4-5 weeks.
I may have one extra for sale if you need one (I charge $200 for 1GB, w/ 32GB microsd and power supply w/ regular shipping included). You would be saving more money directly buying from friendlyElec aliexpress. Only buy from me if you need it fast!