RT-AX86U - Dnsmasq stops resolving DNS addresses

[rlfromm]

Hi All,

For some time now once or twice a week my RT-AX86U with up-to-date stock firmware (3.0.0.4.388_22525) will stop resolving DNS. All active connections will continue to work but if I want to connect to a new location DNS won't resolve to an address. I have traced the issue to Dnsmasq and if I kill Dnsmasq and restart Dnsmasq the issue will go away. The Dnsmasq is version 2.84 in this ASUSWRT distribution. Is anyone else experiencing this issue or has ideas on how to solve this reoccurring problem?

Thanks!

 

[bbunge]

Hi All,

For some time now once or twice a week my RT-AX86U with up-to-date stock firmware (3.0.0.4.388_22525) will stop resolving DNS. All active connections will continue to work but if I want to connect to a new location DNS won't resolve to an address. I have traced the issue to Dnsmasq and if I kill Dnsmasq and restart Dnsmasq the issue will go away. The Dnsmasq is version 2.84 in this ASUSWRT distribution. Is anyone else experiencing this issue or has ideas on how to solve this reoccurring problem?

Thanks!

No issues here. Are you using DoT or DNSSEC? If DNSSEC, disable it. If you use the ISP DNS change to something like Cloudflare.

 

[rlfromm]

No issues here. Are you using DoT or DNSSEC? If DNSSEC, disable it. If you use the ISP DNS change to something like Cloudflare.

DNSSEC is not enabled.

 

[Tech9]

Any errors in logs? Dnsmasq crashing for some reason?

I also have an RT-AX86U and it's working properly. Currently on Asuswrt 388_22525 firmware. My unit is only for experiments though and is not running all the time nor it has many clients attached to it. Perhaps you need to start fresh with factory reset and manual configuration after?

 

[rlfromm]

Any errors in logs? Dnsmasq crashing for some reason?

I also have an RT-AX86U and it's working properly. Currently on Asuswrt 388_22525 firmware. My unit is only for experiments though and is not running all the time nor it has many clients attached to it. Perhaps you need to start fresh with factory reset and manual configuration after?

The factory reset type of action is generally not required for Linux based systems. However, I did do a factory reset just to see if it would make a difference. The factory reset did not resolve the issue.

 

[Tech9]

The factory reset type of action is generally not required for Linux based systems.

This home router with sort of perpetual beta firmware is different than the Linux based systems you perhaps are talking about. I managed to cause reset required condition only playing with firmware settings. I never observed any DNS issues on 388_22525 firmware though.

 

[rlfromm]

Any errors in logs? Dnsmasq crashing for some reason?

I also have an RT-AX86U and it's working properly. Currently on Asuswrt 388_22525 firmware. My unit is only for experiments though and is not running all the time nor it has many clients attached to it. Perhaps you need to start fresh with factory reset and manual configuration after?

It doesn't crash, it just stops resolving IP addresses. I reviewed the logs but there was nothing interesting there for Dnsmasq.

 

[Tech9]

You have to investigate what's causing it on your network. If it was model/firmware related it would be all over SNB Forums.

 

[bbunge]

It doesn't crash, it just stops resolving IP addresses. I reviewed the logs but there was nothing interesting there for Dnsmasq.

What upstream resolver, DNS servers, are you using?

 

[Tech9]

it just stops resolving IP addresses

Set it temporary to Default like this and see how it goes:

 

[Metazoan]

How long do these disruptions last? Do they resolve themselves without intervention on your part?

I've encountered similar behavior, where established connections, like a media stream, will continue uninterrupted, while new queries, like trying to connect to a website, fail.

They last for perhaps 10-20 seconds, then things go back to normal. However, one sure way I've found to resolve them more quickly is to simply log in to the router admin.

The router has been reset multiple times, and with each successive configuration, I've altered fewer and fewer settings from default. I never changed much to begin with except for specifying different DNS servers, but I eventually shifted that to my clients, and left the router with the default DNS settings.

This behavior does seemingly come in waves, so I've resisted blaming it solely on the router, and ruling out an issue with my ISP (AT&T).

Whatever the root cause is, this, and other issues have changed my opinion about Asus, or buying another one of their routers, after having eight rock-solid years with an older model.

 

[rlfromm]

What upstream resolver, DNS servers, are you using?

DHCP assigned from Comcast.

 

[rlfromm]

Set it temporary to Default like this and see how it goes:

View attachment 49622

These are my standard settings.

 

[rlfromm]

How long do these disruptions last? Do they resolve themselves without intervention on your part?

I've encountered similar behavior, where established connections, like a media stream, will continue uninterrupted, while new queries, like trying to connect to a website, fail.

They last for perhaps 10-20 seconds, then things go back to normal. However, one sure way I've found to resolve them more quickly is to simply log in to the router admin.

The router has been reset multiple times, and with each successive configuration, I've altered fewer and fewer settings from default. I never changed much to begin with except for specifying different DNS servers, but I eventually shifted that to my clients, and left the router with the default DNS settings.

This behavior does seemingly come in waves, so I've resisted blaming it solely on the router, and ruling out an issue with my ISP (AT&T).

Whatever the root cause is, this, and other issues have changed my opinion about Asus, or buying another one of their routers, after having eight rock-solid years with an older model.

As I initially reported the issue is permanent unless it kill and restart Dnsmasq which always resolves the issue. Of course a router reboot will accomplish the same thing but a reboot interrupts all traffic. Restarting Dnsmasq is non-disruptive to active connections.

 

[bbunge]

DHCP assigned from Comcast.

Then try something other than Comcast/Xfinity. 1.1.1.2/1.0.0.2 are Cloudflare Security and way better than Comcast. Switching DNS resolvers will not disturb the internet connection.

Am wondering if the DNS cache is not flushing. Defaults to 5,000 entries. Possible the /jffs partition is wonky? Factort reset or Hard Factory Reset may be in order and manual configure.