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
Address: 192.168.1.1
*** 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 (8.8.8.8 and 8.8.4.4) – 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 (8.8.8.8, 8.8.4.4) and until now it works like a charm.