It has WLE200NX a/b/g/n PCIe with antennas (all from PC Engines), plus an Alfa g/n 2000mW adaptor at the end of a long USB cable, positioned for better reception in another building ~150 feet away (n devices are mostly fine without it but especially old b/g devices had a hard time). Before that, wifi had been managed by an RT-N66U, and a repeater had been required to reach the other building. For my setup the APU2 actually replaced 3 devices which had previously been required: Erlite-3 router, RT-N66U, plus repeater. And more to the point, replaced 3 key network infrastructure devices, all running different commercial/closed software, with a single device running a security focused Linux distro and open source boot firmware.
As to load, it manages just a household's worth of machines, maybe ~10 wireless clients and ~10 more devices on the LAN side. The load on the machine is effectively zero. I would personally be confident building such a setup for even 100 clients. The 2 PCI + 2 USB3 offers many expansion options and the SoC itself is tens of times faster than most home routers.
As to load, it manages just a household's worth of machines, maybe ~10 wireless clients and ~10 more devices on the LAN side. The load on the machine is effectively zero. I would personally be confident building such a setup for even 100 clients. The 2 PCI + 2 USB3 offers many expansion options and the SoC itself is tens of times faster than most home routers.