Linksys Velop / Rasp Pi / Pi-hole DNS issue

[S6PNJ]

I'm having a few issues recently with my Rasp Pi Zero 2 W Pi-hole as it keeps randomly crashing and won't allow me to go to the Pi-hole dashboard or login via VNC - that's the issue that then leads me onto the real question. My Linksys Velop mesh system is configured to use the Pi-hole as the DNS. I only have one DNS configured, all other DNS 'fields' are configured to 0.0.0.0

So why, when my Pi-hole crashes (and I see adverts etc, can't browse to the Pi-hole dashboard) am I still able to get to the internet and browse pages I've never looked at before? I've done an 'ipconfig /all' on my laptop and it gives my DNS as 192.168.0.1, ie the IP of my Default Gateway and DHCP server of the Velop mesh node (the node that connects to my FTTP). DNS is still configured as 192.168.0.14 (my Pi-hole address).

Is the Velop Mesh somehow 'finding' a default DNS to allow it to still function? Or why, if my Pi-hole is no longer working, do I get a DNS from somewhere else?

[ARHarh]

I can't help with how your DNS is working. But I can offer advice that is is probably the SD card in your pi that is failing. Take a backup of pihole (if you can) and install to a new card and restore the backup.

[jimmyjimjim]

I'm curious to see if the pi-hole has completely crashed. If you unplug it, can you still reach sites? I'm wondering if it's possible that just some services have stalled, eg VNC and the management interface.

As above though, SD card.

I'm running pi-hole as a container in my NAS. No SD card to corrupt.

[WrekinCrew]

RPi SD cards last longer if you disable Pi-hole logging.

[Chimune]

On the laptop use "nslookup" to get ip of a public domain name and see whats answering

[S6PNJ]

jimmyjimjim said:

I'm curious to see if the pi-hole has completely crashed. If you unplug it, can you still reach sites? I'm wondering if it's possible that just some services have stalled, eg VNC and the management interface.

I've moved my Pi-hole from where it was and also taken it out of the 3D printed case. It is now running about 10 deg C cooler so that might have been the issue causing it to crash, but I'm still none the wiser where my DNS is coming from. Without it crashing again, the only way I can check connectivity is to turn it off and leave all other 'network' settings the same. Having switched the PiHole off and with my DNS in my router still pointing to the RPi, I get connectivity to websites I've not looked at for a long period of time (ie no local cache from using the site today or recently)

Chimune said:

On the laptop use "nslookup" to get ip of a public domain name and see whats answering

On my desktop (Win 11) at the moment but with the PiHole running and connected, if I type n s l o o k u p google.com I get: (had to type like that as I was getting a 403 error)



Server: UnKnown
Address: 2a06:61c1:a2d1:0:ea9f:80ff:fedd:d31f

• * UnKnown can't find google.com: No response from server

With the PiHole switched off (but DNS still pointing to it) I get:



Server: UnKnown
Address: 2a06:61c1:a2d1:0:ea9f:80ff:fedd:d31f

• * UnKnown can't find google.com: No response from server

My Router is configured (RPi PiHole DNS is 192.168.0.14 of course!):

[BlueMR2]

Is the dhcp server giving the .14 address to something else?

Maybe start the dhcp range from .20 instead.

[S6PNJ]

No, nothing else on .14

It's one of a few reserved addresses (11-17 from memory) that I have mapped to MAC addresses.

[Chimune]

I also got 403 error and an offer to translate from Dutch to English when i typed that !
Must be a forum defence technique.

[Chimune]

Mac address can be dynamic so your reservation could fail - which would prob give the dashboard/vnc connection fail symptoms too.
As suggested above, put the pihole in a non dhcp range just to be sure, rather than rely on a reservation
Also you may have reserved ipv4 addr but not the ipv6 one ? Nsl oo kup is failing to get an answer from an ipv6 address.

[jimmyjimjim]

Chimune said:

Mac address can be dynamic so your reservation could fail - which would prob give the dashboard/vnc connection fail symptoms too.
As suggested above, put the pihole in a non dhcp range just to be sure, rather than rely on a reservation
Also you may have reserved ipv4 addr but not the ipv6 one ? Nsl oo kup is failing to get an answer from an ipv6 address.

pihole should definitely be on an address outside of the pool, preferably static.

[S6PNJ]

jimmyjimjim said:

pihole should definitely be on an address outside of the pool, preferably static.

Pi-hole is on a static address.

[Chimune]

Please move the dhcp lower end up to .20. Even if all your reservations and static ips are sound, you need to rule it out.

Then id switch pihole off and try ping-t 192.168.0.14 for 5 mins and check nothing replies. Then switch it on and check it always replies.

[S6PNJ]

DHCP lower end moved to .20

ping-ed the pi whilst switched on, then powered it down (still ping-ing), then rebooted it and I got this:



Why TF did it decide to start pinging .179? That's the address of the computer I was pinging from.

[JoshSm]

S6PNJ said:

Why TF did it decide to start pinging .179? That's the address of the computer I was pinging from.

It didn't, that was the adapter reporting it was unable to reach the actual destination.

[S6PNJ]

JoshSm said:

S6PNJ said:

Why TF did it decide to start pinging .179? That's the address of the computer I was pinging from.

It didn't, that was the adapter reporting it was unable to reach the actual destination.

Ah! of course!