There are (at least) two commonly-available routers that are small, but very powerful. These devices are far superior to typical home routers that are much more expensive.
EdgeRouter-X
RouterBoard hEX
These low-priced power-user devices typically sell for right around $50. The value proposition is compelling.
Ubiquiti Networks EdgeRouter X (ER-X) 5-port Ethernet Gigabit Router
https://www.amazon.com/dp/B0144R449W
https://www.amazon.com/dp/B00YFJT29C
Mikrotik hEX RB750Gr3 5-port Ethernet Gigabit Router
https://www.amazon.com/dp/B01MSUMVUB
The SoC (system-on-chip) hardware in these two routers is very similar and it isn't all that special. What makes these devices work so well is their firmware. Both run Linux variants that are highly optimized for the task at hand.
The Mikrotik runs "RouterOS" and the Ubiquiti runs "EdgeOS". RouterOS is probably capable of higher performance, but it's also probably harder to configure properly. EdgeOS is based on VyattaOS, which has a good reputation.
These routers don't have wireless radios. That's more than acceptable. Your border device arguably shouldn't have wireless anyway. Any consumer wireless router with third-party firmware can be converted into a wireless access point. You can put WAPs anywhere that can be reached with a cable.
Links
- RouterBoard.com : hEX
- It is affordable, small and easy to use, but at the same time comes with a very powerful dual core 880MHz CPU and 256MB RAM, capable of all the advanced configurations that RouterOS supports.
- Ubiquiti Networks - EdgeRouter™ X
- The EdgeRouter™X delivers cost-effective routing performance in an ultra‑compact form factor.
- Mikrotik RouterOS - About RouterOS
- MikroTik RouterOS is the operating system of MikroTik RouterBOARD hardware.
RouterOS demo: http://demo.mt.lv/