I'm having a problem with Dual WAN behavior of the RT-AC66U router. There seems to be an intermittent problem with DNS queries from the clients (tested wireless) behind the router in some cases. It generally works, but fails from time to time.
ASUS RT-AC66U Firmware version 3.0.0.4.376.3754
Dual WAN in Failover mode with Failback
- WAN port (Static IP) - all data given by ISP1, also using Cloned MAC
- Second WAN port on LAN1 port (DHCP) - ISP2
After initially setting up the router out of the box I was offered and did an automatic firmware upgrade to the latest version, but I didn't reset - do I typically need to? I have setup Dual WAN directly and tested with pulling cables from the router and it generally works. Switching in both directions takes a couple of minutes though, please comment how fast should it happen? Watchdog function not activated. Just reloading in the client and after a couple of minutes it starts to work, but definitely not quick and transparent.
After all I stopped experimenting and settled on using the primary WAN port connection leaving the LAN1 port connected.
Then I figured out that DNS queries from clients occasionally fail. If trying to resolve the same address (e.g. www.dropbox.com) several times it eventually works for a minute and then fails again. Meanwhile the connection is stable (e.g. continuous ping), just the DNS resolution fails.
I have rebooted the router, but the DNS problem remains. I have noticed that 192.168.1.1 is given as DNS to my DHCP clients rather than the current ISP DNS address, so the DNS service in the router somehow fails. What kind is the DNS service in the router - passthrough or some kind of caching DNS server?
After turning off Dual WAN configuration, the primary ISP connection on WAN port now works stable without DNS issues.
Any ideas what may be wrong?
ASUS RT-AC66U Firmware version 3.0.0.4.376.3754
Dual WAN in Failover mode with Failback
- WAN port (Static IP) - all data given by ISP1, also using Cloned MAC
- Second WAN port on LAN1 port (DHCP) - ISP2
After initially setting up the router out of the box I was offered and did an automatic firmware upgrade to the latest version, but I didn't reset - do I typically need to? I have setup Dual WAN directly and tested with pulling cables from the router and it generally works. Switching in both directions takes a couple of minutes though, please comment how fast should it happen? Watchdog function not activated. Just reloading in the client and after a couple of minutes it starts to work, but definitely not quick and transparent.
After all I stopped experimenting and settled on using the primary WAN port connection leaving the LAN1 port connected.
Then I figured out that DNS queries from clients occasionally fail. If trying to resolve the same address (e.g. www.dropbox.com) several times it eventually works for a minute and then fails again. Meanwhile the connection is stable (e.g. continuous ping), just the DNS resolution fails.
I have rebooted the router, but the DNS problem remains. I have noticed that 192.168.1.1 is given as DNS to my DHCP clients rather than the current ISP DNS address, so the DNS service in the router somehow fails. What kind is the DNS service in the router - passthrough or some kind of caching DNS server?
After turning off Dual WAN configuration, the primary ISP connection on WAN port now works stable without DNS issues.
Any ideas what may be wrong?
Last edited: