DNS not working directly from router but works fine everywhere else on network - nslookup server 0.0.0.0

[Divader]

I'm getting this odd result when using network tools to do an nslookup on my RT-AC5300:

Pings also just say bad address. Same results over SSH, but when I specify a DNS server to use it works fine eg:

admin@RT-AC5300-7B10-Merlin:/tmp/home/root# nslookup wikipedia.org 9.9.9.9
Server: 9.9.9.9
Address 1: 9.9.9.9 dns9.quad9.net

Name: wikipedia.org
Address 1: 2a02:ec80:300:ed1a::1 text-lb.esams.wikimedia.org
Address 2: 185.15.59.224 text-lb.esams.wikimedia.org

I've been struggling to find a definitive answer anywhere about why it's trying to use 0.0.0.0 - I've put this nowhere in my settings. My rough understanding is that it's some sort of default effectivly the same as 127.0.0.1 (which is what I see when I ping it). This suggests the router is trying to use itself as its primary DNS server, yet everywhere in the GUI I've set other IPs for DNS.

My setup is a bit weird - my asus router (192.168.0.1) used to be the default gateway but is now behind my new ISP router (192.168.0.2) which has become the new gateway after I switched ISP. The ISP router is junk and doesn't support modem mode like my previous ISP router but that's a whole other issue. The asus router is still the DHCP server and my primary DNS server is an Adguard server (192.168.0.184). As far as I can tell everything in the network functions fine except this one router DNS thing but maybe you can spot some stupidity in my config.

Here's output of other commands that may be relevant:

admin@RT-AC5300-7B10-Merlin:/tmp/home/root# cat /etc/dnsmasq.conf
pid-file=/var/run/dnsmasq.pid
user=nobody
bind-dynamic
interface=br0
interface=pptp*
no-dhcp-interface=pptp*
no-resolv
servers-file=/tmp/resolv.dnsmasq
no-poll
no-negcache
cache-size=1500
min-port=4096
domain=zombies
expand-hosts
dhcp-range=lan,192.168.0.25,192.168.0.254,255.255.255.0,86400s
dhcp-option=lan,3,192.168.0.2
dhcp-option=lan,6,192.168.0.184,192.168.0.2,0.0.0.0
dhcp-option=lan,15,zombies
dhcp-option=lan,252,"\n"
dhcp-authoritative
interface=tun21
interface=br1
dhcp-range=br1,192.168.101.2,192.168.101.254,255.255.255.0,86400s
dhcp-option=br1,3,192.168.101.1
interface=br2
dhcp-range=br2,192.168.102.2,192.168.102.254,255.255.255.0,86400s
dhcp-option=br2,3,192.168.102.1
interface=br3
dhcp-range=br3,192.168.103.2,192.168.103.254,255.255.255.0,86400s
dhcp-option=br3,3,192.168.103.1
dhcp-host=18:31:BF:2B:72:BA,set:18:31:BF:2B:72:BA,192.168.0.200
dhcp-host=D4:35:1D:1D:24:71,set4:35:1D:1D:24:71,192.168.0.2
dhcp-host=BC:5F:F4:FE:46:1F,set:BC:5F:F4:FE:46:1F,192.168.0.179
dhcp-host=D0:50:99:17:FC:7E,set0:50:99:17:FC:7E,192.168.0.98
dhcp-host=D2:50:99:2A:84:2D,set2:50:99:2A:84:2D,192.168.0.184
dhcp-option=tag2:50:99C:B3:6C,6,9.9.9.9
dhcp-host=D2:50:99C:B3:6C,set2:50:99C:B3:6C,192.168.0.129
dhcp-host=F0:4D4:43:8E:30,set:F0:4D4:43:8E:30,192.168.0.113
dhcp-name-match=set:wpad-ignore,wpad
dhcp-ignore-names=tag:wpad-ignore
dhcp-script=/sbin/dhcpc_lease
script-arp
edns-packet-max=1232

admin@RT-AC5300-7B10-Merlin:/tmp/home/root# cat /etc/hosts
127.0.0.1 localhost.localdomain localhost
192.168.0.1 RT-AC5300-7B10-Merlin.zombies RT-AC5300-7B10-Merlin
192.168.0.1 RT-AC5300-7B10-Merlin.local
192.168.0.1 www.asusrouter.com
192.168.0.1 asusrouter.com
192.168.0.1 www.asusrepeater.com
192.168.0.1 asusrepeater.com
192.168.0.1 www.asusap.com
192.168.0.1 asusap.com
192.168.0.1 www.asusswitch.com
192.168.0.1 asusswitch.com
192.168.0.1 router.asus.com
192.168.0.1 repeater.asus.com
192.168.0.1 ap.asus.com
192.168.0.1 www.asusnetwork.net
192.168.0.1 asusswitch.net
192.168.0.1 asusrepeater.net
192.168.0.1 asusap.net
192.168.0.1 zenwifi.net
192.168.0.1 expertwifi.net

This is especially annoying as I think it breaks functions like firmware update checks and using a domain name for NTP. What could be going wrong?

 

[dave14305]

Please post the output of:

cat /etc/resolv.conf
nvram show 2>/dev/null | grep -E "^wan.*dns|^wans"

 

[ColinTaylor]

My setup is a bit weird -

Do you have your ISP router plugged into the Asus' WAN port? I suspect not and that that is the reason. When in "router mode" many of the router's functions rely on a working connection to the internet via the WAN port, not a LAN port. Even then, as it stands your router's WAN network is conflicting with its LAN network.

 

[Divader]

Please post the output of:

cat /etc/resolv.conf
nvram show 2>/dev/null | grep -E "^wan.*dns|^wans"

admin@RT-AC5300-7B10-Merlin:/# cat /etc/resolv.conf
admin@RT-AC5300-7B10-Merlin:/#
admin@RT-AC5300-7B10-Merlin:/tmp/etc# ls -l | grep resolv
lrwxrwxrwx 1 admin root 16 May 5 2018 resolv.conf -> /tmp/resolv.conf

It's there but it appears to be an empty file.

Sorry, I forgot to post the other output:

admin@RT-AC5300-7B10-Merlin:/tmp/etc# nvram show 2>/dev/null | grep -E "^wan.*dns|^wans"
wans_cap=wan usb lan
wan0_dns=9.9.9.9 8.8.8.8
wan1_dns1_x=
wans_routing_rulelist=
wan_dns=9.9.9.9 8.8.8.8
wan_dns2_x=8.8.8.8
wans_mode=fo
wan1_dns=
wan_dns1_x=9.9.9.9
wans_dualwan=wan none
wans_lb_ratio=3:1
wan0_dns2_x=8.8.8.8
wans_routing_enable=0
wan0_dnsenable_x=0
wans_lanport=1
wan1_dnsenable_x=1
wan1_dns2_x=
wan_dnsenable_x=0
wans_standby=0
wan0_dns1_x=9.9.9.9
wans_routing_rulelist=

 

[Divader]

Do you have your ISP router plugged into the Asus' WAN port? I suspect not and that that is the reason. When in "router mode" many of the router's functions rely on a working connection to the internet via the WAN port, not a LAN port. Even then, as it stands your router's WAN network is conflicting with its LAN network.

No but I vaguely remember trying this at first and something not working right, so I settled on a lan port. Maybe because there are one or more switches between them?

Conflicting because of being the same network?

 

[bennor]

No but I vaguely remember trying this at first and something not working right, so I settled on a lan port. Maybe because there are one or more switches between them?

Conflicting because of being the same network?

What is the ISP router? Did you configure the ISP router for "bridge mode"? What is the ISP router?
Normally as pointed out by others, you would connect the ISP router to the WAN port of the Asus router not LAN port. Not doing so may cause issues, likely what you are experiencing, where traffic that normally goes out on the Asus router WAN port wouldn't be able to do so.

Edit: Probably best you explain in detail what your Asus router is connected to up stream.

 

[Divader]

What is the ISP router? Did you configure the ISP router for "bridge mode"? What is the ISP router?
Normally as pointed out by others, you would connect the ISP router to the WAN port of the Asus router not LAN port. Not doing so may cause issues, likely what you are experiencing, where traffic that normally goes out on the Asus router WAN port wouldn't be able to do so.

Edit: Probably best you explain in detail what your Asus router is connected to up stream.

It's a Vodafone Vox3.0 THG3000 (Technicolor) heavily customised and locked down to the ISP Vodafone https://openwrt.org/toh/vodafone/vodafone_power_station
It's so bad that it doesn't have an option for bridge mode or anything similar (some settings even inexplicably require the use of a phone app that doesn't work). It's the price I paid for upgrading to fibre I guess.

Yeah the way I've done it is a jank temp solution because I wanted to keep using the superior functions of the asus router and keep it near devices that relied on its switch/wifi. The ISP router was installed at the other side of the house and I've only one cable linking the two places with switches at either end which I need. So to save me running another dedicated cable betwen routers or between the wallmounted fibre box etc. I tried it this way and 99% of things worked so I just left it as something to sort later. I'm basically being cheap and lazy.

TL;DR: asus router wan port empty - connected via a LAN port to a switch which connects to the ISP router, which is connected to the little fibre box on the wall.

 

[Tech9]

so I settled on a lan port

Doesn't work this way. ISP router LAN port -> Asus router WAN port and on a different subnet. You currently have 2x routers on the same network perhaps both running DHCP and offering DNS servers to clients, whichever get first to the client. This creates the mess you experience plus the fact your Asus WAN port is not connected and anything related to this interface is not working.

 

[Tech9]

You have to find a way to do something like this:
(otherwise you Asus can't be a router, but an access point only)

ISP router LAN IP Address - 192.168.0.1
Disable Wi-Fi on the ISP router, disconnect wired clients
Asus router LAN IP Address - 192.168.1.1

ISP router LAN port -> Asus WAN port
Asus WAN IP static 192.168.0.2, subnet mask 255.255.255.0, gateway 192.168.0.1
Place Asus WAN IP 192.168.0.2 in ISP router DMZ

Connect all your devices wired and wireless to the Asus router and configure it the way you want.
This is a common configuration for folks with no Bridge Mode available on the ISP provided equipment.

 

[bennor]

It's a Vodafone Vox3.0 THG3000 (Technicolor) heavily customised and locked down to the ISP Vodafone

TL;DR: asus router wan port empty - connected via a LAN port to a switch which connects to the ISP router, which is connected to the little fibre box on the wall.

See this post (if you haven't seen it already) has some possible suggestions to try and properly put a router behind the Vox3.0:
https://forum.vodafone.co.uk/t5/Oth...-modem-mode/m-p/2708168/highlight/true#M24035

The way you have it setup is the problem. By not using the WAN port with the Asus router set to router mode you are having problems. As already indicated above putting the Asus router into AP mode will disable a number of the router features.

The workaround is to try and find a way to fix the Vox3.0 so you can properly connect it to the Asus router's WAN port NOT it's LAN port. See if the Vox3.0 has a DMZ mode and put the Asus router into that DMZ mode as the above link seems to indicate. Or do what Tech9 suggests in the preceding post.

 

[Ripshod]

The only reason to keep the thg3000 is vodafone's digital voice service. If you're not bothered about it why not just get rid of their router altogether? PPPoE details are freely available from vodafone and you can have any length of cat5e (within reason) between the ONT and the WAN port.
Even if you did want to keep the digital voice service there's a way to do that with a Grandstream ATA.

 

[OzarkEdge]

Even if you did want to keep the digital voice service there's a way to do that with a Grandstream ATA.

Yeah but, if I were going to go to that trouble (managing own ATA), I would switch to less expensive Internet telephony service from a reputable ITSP... a separate project.

OE

 

[Ripshod]

If the OP has had that number for a time they may want to keep it. Porting that number to another service would cancel their broadband, and likely incur a rather substantial early termination fee (we're talking Vodafone UK here).
Just wanted to explore all angles, especially ditching that poor ISP router.

 

[Tech9]

Just wanted to explore all angles...

Good luck exploring this:

I'm basically being cheap and lazy.

 

[Divader]

Doesn't work this way. ISP router LAN port -> Asus router WAN port and on a different subnet. You currently have 2x routers on the same network perhaps both running DHCP and offering DNS servers to clients, whichever get first to the client. This creates the mess you experience plus the fact your Asus WAN port is not connected and anything related to this interface is not working.

What doesn't work? Somehow everything works OK except this one specific niggling thing. I definitely don't have more than one DHCP server running. Never really considered that the status of a wan port could cause such DNS behaviour but it's as good an explanation as any.

You have to find a way to do something like this:
(otherwise you Asus can't be a router, but an access point only)

ISP router LAN IP Address - 192.168.0.1
Disable Wi-Fi on the ISP router, disconnect wired clients
Asus router LAN IP Address - 192.168.1.1

ISP router LAN port -> Asus WAN port
Asus WAN IP static 192.168.0.2, subnet mask 255.255.255.0, gateway 192.168.0.1
Place Asus WAN IP 192.168.0.2 in ISP router DMZ

Connect all your devices wired and wireless to the Asus router and configure it the way you want.
This is a common configuration for folks with no Bridge Mode available on the ISP provided equipment.

Agreed, this is the long term plan.

 

[Divader]

See this post (if you haven't seen it already) has some possible suggestions to try and properly put a router behind the Vox3.0:
https://forum.vodafone.co.uk/t5/Oth...-modem-mode/m-p/2708168/highlight/true#M24035

The way you have it setup is the problem. By not using the WAN port with the Asus router set to router mode you are having problems. As already indicated above putting the Asus router into AP mode will disable a number of the router features.

The workaround is to try and find a way to fix the Vox3.0 so you can properly connect it to the Asus router's WAN port NOT it's LAN port. See if the Vox3.0 has a DMZ mode and put the Asus router into that DMZ mode as the above link seems to indicate. Or do what Tech9 suggests in the preceding post.

Thanks, the thread is relatable haha. I'll look more into this 'open host function' option as it was an idea I'd initially condsidred but wanted make sure I knew all the security implications 1st.

 

[Divader]

The only reason to keep the thg3000 is vodafone's digital voice service. If you're not bothered about it why not just get rid of their router altogether? PPPoE details are freely available from vodafone and you can have any length of cat5e (within reason) between the ONT and the WAN port.
Even if you did want to keep the digital voice service there's a way to do that with a Grandstream ATA.

Good question; getting rid of it was the first thing I wanted to do with it - not so bothered about the landline as it cost no extra but would be nice to have I suppose. To my amazement I did actually get their PPPoE details from chat support (after a million hours of phone hell) but my hopes were dashed after I put them in my own router (connected up correctly) and they simply didn't work. I've been meaning to try my luck with another support person but I'm losing motivation to try that again.

To add to the mix they supplied a wifi booster that is locked down to it and a 4G dongle which may or may not be usable on anything.

 

[Tech9]

Somehow everything works OK

Your Asus router has LAN ports and Wi-Fi interfaces bridged internally. It works as a switch at the moment, your network is driven by the ISP router. This is what you have working OK. Your WAN settings on the Asus do nothing and none of the routing related features actually work on this device. Networking doesn't work this way - connect some ports and see what happens. Better run this Asus router in AP Mode temporary until you fix the wires situation.

 

[Ripshod]

Good question; getting rid of it was the first thing I wanted to do with it - not so bothered about the landline as it cost no extra but would be nice to have I suppose. To my amazement I did actually get their PPPoE details from chat support (after a million hours of phone hell) but my hopes were dashed after I put them in my own router (connected up correctly) and they simply didn't work. I've been meaning to try my luck with another support person but I'm losing motivation to try that again.

To add to the mix they supplied a wifi booster that is locked down to it and a 4G dongle which may or may not be usable on anything.

Try again with the pppoe details they gave you. Use VLAN 911 if your connection is cityfibre, no VLAN if it's openreach, 101 if it's Kingston Communications.
Username should have 9 numbers in it

dslXXXXXXXXX@broadband.vodafone.co.uk

password is 15 digits.