DNS resolving Issues with ASUS RT-AC87U

I recently bought an new Router – the ASUS RT-AC87U.

I used it for some weeks with no problems, unless I tried to insert my 3G Data-Stick into the USB-Port (for failover reasons).

Since then, I did have occasional problems in resolving various internet adresses.

PS C:\Users\Harald> nslookup orf.at
Server: router.asus.com

*** orf.at wurde von router.asus.com nicht gefunden: Query refused.

Query refused? At first, I blamed my provider, and tried to configure the dns-adresses in the router to the Google-DNS-Servers ( and – unfortunately this did not help. The same error messages appeared and appeard. Refreshing the Site in the browser did help in most cases.

The Asus-Routers uses the dnsmasq DNS-Deamon to act as a DNS-Server. However, the DNS-Servers the deamon uses itsself are in the /etc/resolv.conf file. And there lies the magic (or the root of my problem).

If the router gets the (2) DNS-Servers Adresses from the Provider, it stores these IPs in the resolv.conf file. If you configure DUAL-WAN, you will get 4 DNS-Adresses into the file (2 for each provider). Providers usually only allow DNS-Queries from there own network…

So in some cases, the router uses WAN-Connection from Provider A, but tries to resolve the addresses with the DNS-Server from Provider B – which then gets refused.

What did I do?

I set the DNS-Server Adresses manually in /etc/resolv.conf via vi to only two entries (, and until now it works like a charm.