[DNS resolve problem] No internet after connecting PiHole

[amratya01]

Description:

I have installed PiHole on RP0w, changed DNS settings on my router to make all clients resolve domains from it. After that, I wanted to install PiVPN to be able to get the max of it to the outer network as well, but it failed to connect for some reason. So, I decided to remove PiVPN and find a solution later. Long story short, the internet didn't work afterward.

I checked the debug report and I found out that PiHole couldn't resolve domains for some reason! while it can resolve

*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✓] azurezerohentai.blogspot.sk is 0.0.0.0 via localhost (127.0.0.1)
[✗] Failed to resolve azurezerohentai.blogspot.sk via Pi-hole (192.168.0.124)
[✓] doubleclick.com is 172.217.16.78 via a remote, public DNS server (8.8.8.8)

*** [ DIAGNOSING ]: Name resolution (IPv6) using a random blocked domain and a known ad-serving domain
[✓] tubaolic.com is :: via localhost (::1)
[✗] Failed to resolve tubaolic.com via Pi-hole (2a02:8109:8340:5e90:a554:d2d0:372f:2a71)
[✗] Failed to resolve doubleclick.com via a remote, public DNS server (2001:4860:4860::8888)

Possible solutions tried:

pi@raspberrypi:~ $ dig google.com @127.0.0.1

; <<>> DiG 9.11.5-P4-5.1+deb10u2-Raspbian <<>> google.com @127.0.0.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62474
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;google.com.			IN	A

;; ANSWER SECTION:
google.com.		231	IN	A	216.58.213.238

;; Query time: 1 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Sep 03 12:03:37 CEST 2020
;; MSG SIZE  rcvd: 55

pi@raspberrypi:~ $ dig google.com @192.168.0.124

; <<>> DiG 9.11.5-P4-5.1+deb10u2-Raspbian <<>> google.com @192.168.0.124
;; global options: +cmd
;; connection timed out; no servers could be reached

multiple restart
pihole -r
changed the /etc/resolv.conf to 8.8.8.8 instead of 127.0.0.1

Debug Token:

token is: https://tricorder.pi-hole.net/bcjcpzh2g8

[amratya01]

Found out the problem.

from the Admin page it was selected to Listen on all interfaces, permit all origins

which is declared beneath:
Note: that the last option should not be used on devices which are directly connected to the Internet. This option is safe if your Pi-hole is located within your local network, i.e. protected behind your router, and you have not forwarded port 53 to this device. In virtually all other cases you have to make sure that your Pi-hole is properly firewalled.

Changed it back to Listen only on interface wlan0 and it worked.