I'm using my Asus DSL-AC68U for openvpn with my devices when in Korea. It seems to work sufficiently. I have a similar line sync and throughput to the OP and the Asus was relatively stable (no drop outs anyway). Although it lost 5-7Mb sync rate to keep it stable along with the SNR fluctuat a fair bit. It is currently being used as a router only with a HG612 doing the modem side of things.
Asus routers only use PPTP or OpenVPN though from what I found.
You both using Infinity 2 though if you over 40Mb download speeds so you should not have any issues with IP address sharing etc )))
