DNS resolution slowness on RT-AC56U?!

[TheImmortal]

Hello everyone,

I've been reading you guys for close to a month now and kudos to you, the community, and to you, RMerlin, for what you've done! I've gotten my hands on an RT-AC56U ever since my ISP started giving out 1000mbps connections and, whilst I love its throughput power, it's USB 3.0 (35MB/s constantly!) and it's firmwares (using Merlin's latest), I can't stop but be amazed of an issue I have never seen on the Linksys E2000, DiR 615 or even on direct PPPoE: an annoying DNS resolution slowness.

I can't really replicate it. Whenever I try to hit up a new page, I'm getting some 5-10seconds of 'waiting to resolve'; sometimes I'm even getting the 'page timeout' on Firefox/Chrome on websites that I KNOW THAT work and resolve fine. And then if I hit refresh, it all magically works. Overall, I'm sensing a lack of speed when it comes to the HTTP handshake, with everything 'waiting for a bit' before it starts.

Is it 'an ok router'? I have 4 more days to give it back and change it 'no questions asked' and I wonder if I shouldn't be doing it. I've gotten it at a promo and it is already a bit expensive for my budget (and, I felt, needs) but the dualWAN and USB 3.0 + WAN throughput sold me. Unfortunately, this slowness kinda 'makes it up for all of it'.

Does anyone have any ideas? I'm using Merlin's 374.42_2 and went on two ASUS firmwares previously, but spotted no real changes. Doing a traceroute from SSH starts INSTANTLY, whilst if I do it from my computer's OS (connected to the router via LAN), it takes for it 20-25seconds to do the first hop but the values are very low and don't really show any of the issues I'm getting.


Thank you.

 

[RMerlin]

To rule out resolution issues, do a few tests using nslookup on the affected computer. You will see if that's where it gets hung.

Make sure your computer doesn't have any invalid static DNS configured. Windows can sometime bug out and keep a "ghost" DNS memorized in addition to those provided by DHCP. You can check using "ipconfig /all".

Also make sure your computer isn't trying to use IPv6 while your router wouldn't be configured for that.

 

[TonyH]

Hi,
Just for fun run a pass of namebench. My local ISP DNS is slower than one in next city...
Isn't that funny?

 

[TheImmortal]

Ok I think this nslookup confirms it:

PS C:\Windows\system32> nslookup nba.com
DNS request timed out.
timeout was 2 seconds.
Server: UnKnown
Address: 192.168.18.10

DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
Non-authoritative answer:
Name: nba.com
Addresses: 157.166.249.247
157.166.248.245

PS C:\Windows\system32> nslookup nba.com
Server: UnKnown
Address: 192.168.18.10

Non-authoritative answer:
Name: nba.com
Addresses: 157.166.248.245
157.166.249.247


192.168.18.10 is the DNS of my VPN server, which should ONLY be used for two internal websites and shouldn't kick in:

PS C:\Windows\system32> ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : Immortals
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

PPP adapter fortissl:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : fortissl
Physical Address. . . . . . . . . :
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 10.254.251.102(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . :
DNS Servers . . . . . . . . . . . : 192.168.18.10
192.168.17.2
NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Ethernet:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller
Physical Address. . . . . . . . . : 6C-F0-49-71-A6-F8
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 192.168.1.139(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Friday, May 23, 2014 6:46:08 AM
Lease Expires . . . . . . . . . . : Saturday, May 24, 2014 6:46:04 AM
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DNS Servers . . . . . . . . . . . : 192.168.1.1
NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter VirtualBox Host-Only Network:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : VirtualBox Host-Only Ethernet Adapter
Physical Address. . . . . . . . . : 08-00-27-00-14-CB
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::ed66:6fdc:dfcd:a8e1%7(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.56.1(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . :
DHCPv6 IAID . . . . . . . . . . . : 168296487
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-F3-A3-1E-6C-F0-49-71-A6-F8
DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1
fec0:0:0:ffff::2%1
fec0:0:0:ffff::3%1
NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter isatap.{E355B341-A309-4076-8535-9FD93B63B904}:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter isatap.{2DF4DBF8-CB91-4536-9F55-C814ED5E6549}:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter isatap.{545144C9-D6B8-45AE-AB9F-10F058D94D83}:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter #3
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Mkey, this is now looking like a local PC issue, but I don't really get why it happens on my wife's laptop too (she has no fortinet VPN).

I would have considered using google's public DNS, but the router seems to nslookup everything instantly:
admin@RT-AC56U:/# nslookup nba.com
Server: 127.0.0.1
Address 1: 127.0.0.1 localhost.localdomain

Name: nba.com
Address 1: 157.166.248.245
Address 2: 157.166.249.247


LE: I will give it an extended try later today, once I'm done with work, without the VPN and, if the issue persists, with the cable directly into the computer to rule out the router. Will restart the PC each time to prevent issues generated by hanging DNS records and will post the updates as soon as I get the chance.
I'd hate to return it for no valid reason.

 

[RMerlin]

You are trying to use 192.168.18.10 as your DNS, while your router is on 192.168.1.1. There's your problem. It comes from that VPN connection you have.

 

[TheImmortal]

Mwell I am not...the computer is trying to. Which I don't really see why :/

The fact that I got in a SSD with the router probably adds to the general idea; the moment i switched from my E2000 to the new RT-AC56U coincides with the moment I upgraded my OS from a Win7 on a 10k rpms drive to Win8.1 on a SSD. A Win7 that, with the very same VPN installed (it's a work VPN...), worked fine. Very fine.

I need to dig deeper, the VPN should only kick in when TWO (thats it - just two!) hostnames are used.

 

[RMerlin]

Mwell I am not...the computer is trying to. Which I don't really see why :/

The fact that I got in a SSD with the router probably adds to the general idea; the moment i switched from my E2000 to the new RT-AC56U coincides with the moment I upgraded my OS from a Win7 on a 10k rpms drive to Win8.1 on a SSD. A Win7 that, with the very same VPN installed (it's a work VPN...), worked fine. Very fine.

I need to dig deeper, the VPN should only kick in when TWO (thats it - just two!) hostnames are used.

DNS resolution is done before any routing is being done, since the computer has no idea at that point which IP the name will belong to. Windows can then end up trying to resolve with whichever DNS you have configured on the VPN tunnel.

Remove that DNS from your VPN connection, or correct it so it will be within your subnet, and it should resolve your issue. I suspect your previous router might have been configured for that other subnet, which would explain why the issue only appeared after switching routers.

Description . . . . . . . . . . . : fortissl
...snip...
DNS Servers . . . . . . . . . . . : 192.168.18.10
192.168.17.2

 

[TheImmortal]

Yeap, that's it, thank you very much for the assistance. It works perfectly fine when I DONT connect that VPN (say 'when im not @work'), but it slows to the point of becoming annoying when I do connect it. I'm having no options to change the DNS for it so I don't really know how to fix it, plus i think the E2000 used the same 192.168.1.1 subnet.

Could be the OS, could be just the crappy VPN client. But it's definitely not the router