Slow DNS?

Post new topic   Reply to topic    DD-WRT Forum Forum Index -> General Questions
Goto page 1, 2  Next
Author Message
rrm74001
DD-WRT Novice


Joined: 22 Aug 2019
Posts: 8

PostPosted: Sat Sep 12, 2020 1:42    Post subject: Slow DNS? Reply with quote
I have 2 devices on my network that are suddenly unhappy using my router (192.168.1.1) as a DNS. These devices are a Samsung Smart TV and an Apple TV. I found that if I override the DHCP provided DNS address (192.168.1.1) on these devices to use a public DNS server directly (like 8.8.8.8) they magically start working. The thing is my router is already pointing to these public DNS servers anyway and should just be forwarding on the DNS queries so I am not really sure why this would make a difference for these 2 devices. Most other devices on my network do not seem to have a problem using my router as a DNS.

The only thing I can think of is maybe the router DNS is introducing some latency that these 2 devices in particular are sensitive to? Doing an nslookup on my laptop, it does sometimes take a good 5 seconds to get a response. I guess I am not really sure where to start looking to figure out what is going on here...

Router Model: Netgear R7800
Firmware: DD-WRT v3.0-r40559 std (08/06/19)



Last edited by rrm74001 on Sat Sep 12, 2020 13:07; edited 1 time in total
Sponsor
Alozaros
DD-WRT Guru


Joined: 16 Nov 2015
Posts: 3883
Location: UK, London, just across the river..

PostPosted: Sat Sep 12, 2020 2:05    Post subject: Reply with quote
if those are androids have a look here

https://forum.dd-wrt.com/phpBB2/viewtopic.php?p=1216552&highlight=#1216552

also not bad to start with router model and current firmware build running...
Embarassed

_________________
Atheros
TP-Link WR740Nv1 -----DD-WRT 44538 BS AP,NAT
TP-Link WR740Nv4 -----DD-WRT 44251 BS WAP/Switch
TP-Link WR1043NDv2 ---DD-WRT 44627 BS AP,NAT,AP Isolation,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 ---DD-WRT 44538 BS AP,NAT,AD Block,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 ---Gargoyle OS 1.12.0 AP,NAT,QoS,Quotas
Qualcomm/IPQ8065
Netgear R7800 -----DD-WRT 44538 BS AP,NAT,AD-Block,AP&Net Isolation,VLAN's,Firewall,Local DNS,DoT
Broadcom
Netgear R7000 -----DD-WRT 44538 BS AP,Wi-Fi OFF,NAT,AD-Block,Firewall,Local DNS,Forced DNS,DoT,VPN
-----------------------------------------------------------------------------------------------
Stubby for DNS over TLS I DNSCrypt v2 by mac913
msoengineer
DD-WRT Guru


Joined: 21 Jan 2017
Posts: 1369
Location: Illinois Moderator

PostPosted: Sat Sep 12, 2020 2:08    Post subject: Reply with quote
you need to check forced DNS redirection and click ignore wan DNS at the top of the main setup tab
_________________
FORUM RULES

TIPS/TRICKS: Best QCA Wifi Settings | Latency tricks | QoS Port priority | NEVER USE MU-MIMO |
Why to NOT use MU-MIMO | Max Wifi Pwr by Country | Linux Wifi Pwr | AC MCS & AX MCS | QCA 5Ghz chnls to use | WIFI Freq WIKI | TFTP R7800 | Don't buy AX | IPERF3 How-To

[R9000]44565 nightly (Main Router)
[EA8500]43192 nightly (2xOffsite)
[R7800]napping
[WDR3600]BS 42567 (Offsite)
[A7v5]BS 43038 (Offsite+spare napping)
rrm74001
DD-WRT Novice


Joined: 22 Aug 2019
Posts: 8

PostPosted: Sat Sep 12, 2020 13:53    Post subject: Reply with quote
msoengineer wrote:
you need to check forced DNS redirection and click ignore wan DNS at the top of the main setup tab




Ignore WAN DNS - I do not seem to have this option.

Force DNS Redirection - I am not sure why that would help? If a client is already configured to use the router as DNS then this just seems redundant.
msoengineer
DD-WRT Guru


Joined: 21 Jan 2017
Posts: 1369
Location: Illinois Moderator

PostPosted: Sat Sep 12, 2020 14:29    Post subject: Reply with quote
You're using a known bad build upgrade to something from 2020 like 44187.
_________________
FORUM RULES

TIPS/TRICKS: Best QCA Wifi Settings | Latency tricks | QoS Port priority | NEVER USE MU-MIMO |
Why to NOT use MU-MIMO | Max Wifi Pwr by Country | Linux Wifi Pwr | AC MCS & AX MCS | QCA 5Ghz chnls to use | WIFI Freq WIKI | TFTP R7800 | Don't buy AX | IPERF3 How-To

[R9000]44565 nightly (Main Router)
[EA8500]43192 nightly (2xOffsite)
[R7800]napping
[WDR3600]BS 42567 (Offsite)
[A7v5]BS 43038 (Offsite+spare napping)
rrm74001
DD-WRT Novice


Joined: 22 Aug 2019
Posts: 8

PostPosted: Sat Sep 12, 2020 16:31    Post subject: Reply with quote
msoengineer wrote:
You're using a known bad build upgrade to something from 2020 like 44187.



Holy moly! Build 40559 is the newest available when I look in the router database but yeah I see newer builds when I look in general downloads. I will try upgrading later today!

https://dd-wrt.com/support/router-database/?model=R7800_v1
Zyxx
DD-WRT User


Joined: 28 Dec 2018
Posts: 279

PostPosted: Sat Sep 12, 2020 22:30    Post subject: Reply with quote
Yeah,

the database isn't up to date and might behave like it was stated on the website Wink :

Code:

DISCLAIMER
This database may not have up-to-date information and may even recommend a build which might cause issues. As such, you should check the device specific forum (Broadcom, Atheros, MediaTek, etc.) first before flashing any build recommended in this database. There you will find build specific topics that discuss any issues with a particular build/release. For more up-to-date firmware files, please visit the firmware faq.
rrm74001
DD-WRT Novice


Joined: 22 Aug 2019
Posts: 8

PostPosted: Sun Sep 13, 2020 0:49    Post subject: Reply with quote


Okay, upgraded. I will see now if my issue persists.


Last edited by rrm74001 on Sun Sep 13, 2020 3:15; edited 1 time in total
rrm74001
DD-WRT Novice


Joined: 22 Aug 2019
Posts: 8

PostPosted: Sun Sep 13, 2020 1:41    Post subject: Reply with quote
Okay, even after upgrade, the Samsung Smart TV is still unhappy using the router as DNS.
Alozaros
DD-WRT Guru


Joined: 16 Nov 2015
Posts: 3883
Location: UK, London, just across the river..

PostPosted: Sun Sep 13, 2020 13:49    Post subject: Reply with quote
rrm74001 wrote:
Okay, even after upgrade, the Samsung Smart TV is still unhappy using the router as DNS.


add those lines in commands>firewall script

iptables -t nat -I PREROUTING -i br0 -s 192.168.xxx.xxx -p udp --dport 53 -j DNAT --to 8.8.8.8


iptables -t nat -I PREROUTING -i br0 -s 192.168.xxx.xxx -p tcp --dport 53 -j DNAT --to 8.8.8.8

also add static IP to your SSNG TV and replace its ip in those lines...
you can use other DNS than GGL, but try with GGL if so...im using 9.9.9.9 with no problems as well i have "Forced DNS" turned on too...

_________________
Atheros
TP-Link WR740Nv1 -----DD-WRT 44538 BS AP,NAT
TP-Link WR740Nv4 -----DD-WRT 44251 BS WAP/Switch
TP-Link WR1043NDv2 ---DD-WRT 44627 BS AP,NAT,AP Isolation,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 ---DD-WRT 44538 BS AP,NAT,AD Block,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 ---Gargoyle OS 1.12.0 AP,NAT,QoS,Quotas
Qualcomm/IPQ8065
Netgear R7800 -----DD-WRT 44538 BS AP,NAT,AD-Block,AP&Net Isolation,VLAN's,Firewall,Local DNS,DoT
Broadcom
Netgear R7000 -----DD-WRT 44538 BS AP,Wi-Fi OFF,NAT,AD-Block,Firewall,Local DNS,Forced DNS,DoT,VPN
-----------------------------------------------------------------------------------------------
Stubby for DNS over TLS I DNSCrypt v2 by mac913
rrm74001
DD-WRT Novice


Joined: 22 Aug 2019
Posts: 8

PostPosted: Sun Sep 13, 2020 14:14    Post subject: Reply with quote
But why is my Samsung TV special that I have to do firewall hacks to get it to work? What is the difference between the client sending DNS queries to 192.168.1.1 and the router forwarding on to 8.8.8.8 compared to the client sending the DNS queries directly to 8.8.8.8?

I also noticed last night that my Raspberry Pi has the same problem.
Alozaros
DD-WRT Guru


Joined: 16 Nov 2015
Posts: 3883
Location: UK, London, just across the river..

PostPosted: Sun Sep 13, 2020 16:16    Post subject: Reply with quote
to answer your question, i shall ask... did you read the link i posted above....?? Laughing
_________________
Atheros
TP-Link WR740Nv1 -----DD-WRT 44538 BS AP,NAT
TP-Link WR740Nv4 -----DD-WRT 44251 BS WAP/Switch
TP-Link WR1043NDv2 ---DD-WRT 44627 BS AP,NAT,AP Isolation,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 ---DD-WRT 44538 BS AP,NAT,AD Block,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 ---Gargoyle OS 1.12.0 AP,NAT,QoS,Quotas
Qualcomm/IPQ8065
Netgear R7800 -----DD-WRT 44538 BS AP,NAT,AD-Block,AP&Net Isolation,VLAN's,Firewall,Local DNS,DoT
Broadcom
Netgear R7000 -----DD-WRT 44538 BS AP,Wi-Fi OFF,NAT,AD-Block,Firewall,Local DNS,Forced DNS,DoT,VPN
-----------------------------------------------------------------------------------------------
Stubby for DNS over TLS I DNSCrypt v2 by mac913
rrm74001
DD-WRT Novice


Joined: 22 Aug 2019
Posts: 8

PostPosted: Tue Sep 15, 2020 17:46    Post subject: Reply with quote
Alozaros wrote:
to answer your question, i shall ask... did you read the link i posted above....?? Laughing


Sorry if I missed it, but what was I supposed to get from that link? I see that the issue and "fix" is similar to mine, but I don't see an explanation as to why this is a problem.

If you are implying that my Samsung TV is built on top of Android and so prefers using 8.8.8.8, I can actually use any other DNS (4.2.2.2, 1.1.1.1, 9.9.9.9, 208.67.222.222, etc...), the problem is only when using 192.168.1.1 as DNS. And obviously, my Apple TV is not built on top of Android to begin with.
egc
DD-WRT Guru


Joined: 18 Mar 2014
Posts: 6408
Location: Netherlands

PostPosted: Tue Sep 15, 2020 17:54    Post subject: Reply with quote
Maybe the Android appliance regards the use of a DNS server in the same subnet as a rebind attack and will not use this?
_________________
Routers:Netgear R7800, R6400v1, R6400v2, Linksys EA8500, EA6900 (XvortexCFE), E2000 (converted WRT320N), WRT54GS v1.
OpenVPN Policy Based Routing: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=321686
Install guide R6400v2:http://forum.dd-wrt.com/phpBB2/viewtopic.php?t=316399
OpenVPN Server Setup:https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=318795
Install guide R7800: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=320614
Wireguard Server setup guide:https://forum.dd-wrt.com/phpBB2/viewtopic.php?p=1183135
Wireguard Client setup guide:https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324624
Wireguard Advanced setup guide:https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324787
Forum Guide Lines (important read):https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324087
rrm74001
DD-WRT Novice


Joined: 22 Aug 2019
Posts: 8

PostPosted: Wed Sep 16, 2020 0:14    Post subject: Reply with quote
egc wrote:
Maybe the Android appliance regards the use of a DNS server in the same subnet as a rebind attack and will not use this?


Interesting idea, but seems like a poor design decision if true. Surely most people's DHCP setups tell clients to use the router/gateway for DNS.
Goto page 1, 2  Next Display posts from previous:    Page 1 of 2
Post new topic   Reply to topic    DD-WRT Forum Forum Index -> General Questions All times are GMT

Navigation

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum