pi-hole + unbound setup blocks a single device from accessing the internet

Help
1

Recently set up a Pi-hole on a Pi 3B+ and also configured unbound to work with it. It worked for about 2 days perfectly until today when a power cut happened and when the power came back, only my laptop was not able to connect to any site except the pi-hole dashboard.

I checked the queries, some apps like Discord were sending queries but the app never loaded in, most were Microsoft queries (windows installation on laptop, the queries were I'm pretty sure to check the internet access of the WiFi as they stopped as soon as the "Internet access" icon popped up on the taskbar) which stopped after a small while and I did not find any other queries (for example to Google when I tried loading Google to test the internet) in the query list.

How I fixed it: (temporarily)

As expected forcing the DNS to be another upstream DNS like Cloudflare let me use the internet again. Then I tried putting the dns caching value in the pi-hole dashboard to 0 and everything went back to normal even with the pi-hole DNS. Of course, I can't go around clearing the cache every single time my pi-hole turns off, so I'm wondering if the cache gets corrupted whenever the pi turns off suddenly. But in that case, wouldn't all my devices be affected??

Also, nslookup returned "server not found" for any and all domains I tried

(I am a newbie, please do not judge)

Expected Behaviour:

For my laptop to be able to access the internet the same as my other devices.

  • Raspberry Pi OS Lite
  • Raspberry Pi 3B+

Actual Behaviour:

Singular device not able to access the internet at all.

Debug Token:

https://tricorder.pi-hole.net/rxpuRGcM/ (I suppose this is it??)

2

All Raspberry Pi's don't like sudden loss of power in general and my guess is that besides the file system (in general on a microSDXC card) other things can easily get corrupted too :slight_smile:

Indeed, so that's a bit weird in this case...

3

@aksv

Your debug log shows the router is advertising itself as DNS server:

  router: 192.168.1.1
  dns-server: 192.168.1.1
  server-identifier: 192.168.1.1

Are you sure the laptop is using Pi-hole as DNS server?

Also, I can see you are using tailscale. Please check if the laptop is trying to use tailscale when the connection fails.

When the issue happens, do you actually see the requests from your laptop as Blocked, on the Query Log page? Or the device simply doesn't access the Internet and you suspect this is a Pi-hole issue?

Next time it happens, please execute this commands from your laptop and post the output here:

nslookup google.com

nslookup google.com 192.168.1.4

nslookup google.com 192.168.1.6

Then check the query log to see if these queries are there.