Enabling OpenVPN Server on RT-AC66U Results in router running at 100 percent CPU

I have an RT-AC66U router. With the latest official ASUS FW release, as well as all before it, I can't get OpenVPN server to work with my Mac. I understand the issue to be related to the dhparams.pem key being 512 bits, when OpenSSL on the Mac now requires 2048 bits. Several forum posts elsewhere suggest that you can create a 2048 bit key on Linux or OS X and paste it into the appropriate ASUS router field. However, I was never able to get the router to accept the longer key. After...

Enabling OpenVPN Server on RT-AC66U Results in router running at 100 percent CPU