1. Install Astrill applet on Asus router
2. Choose RouterPro VPN UDP protocol (usually at least 2x speeds).
3. Select Singapore 1 USA server (best server for US streaming to be used in SG).
On Asus RT-AC56U hardwired to my PC, I am getting 80Mbps (on VQ) running speedtest with the above setup. In such case latency matters, so the closer the server the better speeds you will achieve. If you connect to US servers it might drop to 20Mbps (or 10-15Mbps on normal OpenVPN protocol, not RouterPro).
Usually beside latency, CPU of the router is a bottleneck. Try desktop app to see a difference.