rt-ac56u using openvpn-forced dns redirection by isp

[pattox]

I'm using the latest version of the Merlin firmware on an rt-ac56u. I need to use the vdsl modem/router supplied by my isp. My landline is now voip and the supplied modem router is needed to make my voip service work because the sip voip settings are encrypted. Consequently I have to use their router at the moment.
The fundamental problem I have is that the isp has programmed this router to automatically redirect all dns requests to its own dns servers. Consequently, even when using VPN the dns shows as that of my isp rather than my vpn service.

I've tried different settings in the Asus router but so so I haven't been able to stop this forced redirection.

I'm wondering if there is a way to fix this?

 

[L&LD]

Have you tried using the voip settings available on the 'AC56U instead? I'm pretty sure you don't 'need' the ISP supplied router just for that.

 

[pattox]

Have you tried using the voip settings available on the 'AC56U instead? I'm pretty sure you don't 'need' the ISP supplied router just for that.

I tried "exclusive" in the (VPN/Openvpn advanced settings/accept dns configuration) and that didn;t work.

Later I came across the following
http://www.snbforums.com/threads/openvpn-dns-leaking.25295/

There RMerlin's simple answer was to set up a DNSfilter.

I found this under the AiProtection/DNS filter section in the router and chose the Opendns Home setting. That worked!