Slow vpn speed after Asus WRT merlin update in Troubleshooting and Problems Posted ... What data cipher is being used now? Which one was being used? I mean, look in the system log to see what actually happened. It sounds like you have an ac86 or one of the asus routers with AES-NI. So, you maybe need to make sure to use an AES encryption though chacha20 (available with openvpn 2.5) may be fast too. Is it possible that AES-NI acceleration has been disabled? Have you asked this in Merlin support forum?