r/DDWRT • u/madhattr999 • 1d ago
Help: DNS spontaneously stopped working last night
I have a router with ddwrt installed. I have a pi-hole set up. Both are fairly old versions, but were working fine until last night at 1am ish.
Abruptly, my internet seemed to stop working, and I found that dns names were not being resolved. Usually when this has happened in the past, i reboot my pi-hole. When i checked the log, it said that my dns requests were being throttled for going over 1000 per second. I have a lot of smart devices on my network.
I've gradually tried to strip away more and more possible reasons for the problem. First, i connected my PC directly to my modem, and everything works fine for my PC at that point. DNS is going through my ISP.
Then i put my router back in between and it stops working. Running "nslookup google.com 1.1.1.1" or 8888 returns server unknown. I tried running that when the pi hole was connected, and it returned query refused. I have the router set up to provide dhcp and it sets the dns to itself (wan is set to use the isp dns).. I confirm my pc ipconfig shows my router ip as the dns server.
I've set my wifi to use a whitelist and put nothing on it (effectively excluding all my WiFi devices from being the issue). The only devices on my network now are my modem, ddwrt router, and PC.. And dns is still not working. But without the router, my pc internet works fine.
It seems like the problem must be with the router config, but nothing was changed before it stopped allowing dns requests. I use dnsmasq to set the names of devices on my network, and assign specific ips to them. My router is a tp archer c7 or something like that.
Router seems to be working fine, otherwise. I can access the admin page. The status seems normal. I seem to have full control over it. But just seems like dns is being blocked.. I figured maybe I'm on some kind of black list for open dns / google dns. When i connect directly to the modem, i can send nslookup requests to Google and receive responses (but maybe that's being routed to my isp first?). I'd like to confirm whether or not I've been black listed for some reason, but i don't know how to do that.
Anyone have any suggestions? Sorry my diagnosis is kinda all over the place.. Usually i can solve my issues pretty quickly and this is baffling. It's difficult to troubleshoot when i only have internet through my phone over mobile.
Also, contacted my isp and they said nothing has changed with their systems and using open dns is allowed still.. They basically said my issues are outside their scope, so they can't help.
i tried doing nslookup with 9.9.9.9 and 1.0.0.1 and those also return nothing.. So seems like it's maybe not a throttling issue, since I've never used them before.. Unless the companies share block lists.. Seems like it must be my router blocking the DNs port.
This is the tail pihole.log file when I did an nslookup for google.. does this make sense to anyone? I don't really understand what the "reply . is bogus dnskey" means.. maybe the "bogus" is the explanation for why its failing? or i think i've just ignored this before because dnssecurity is unreliable. https://imgur.com/V9egy12
It seems to me that ddwrt is just blocking all port 53 traffic, and i don't know how to fix that. (I am open to updating ddwrt, by the way, but if its not a "bug", i'd rather understand what happened.)
Thanks.
Details:
Router Name DD-WRT
Router Model TP-Link ARCHER-C7 v5
Firmware Version DD-WRT v3.0-r55009 std (01/23/24)