Intermittent DNS timeouts with PiHole

Apps and Virtualization
1

I’m have been using PiHole on a Raspberry Pi 3B for years as my network’s DNS without issues. The PiHole address was configured on the network’s router as the DNS address, so that all clients using DHCP would automatically use the PiHole as their DNS.

I recently installed PiHole on TrueNas (Electric Eel - 24.10.0.2) and changed my router’s DNS address to point to the TrueNas server. Since then, several devices have had intermittent DNS timeouts that make simple web browsing very annoying.

However, if I manually configure the clients DNS setting (leaving the rest to DHCP) to point to the TrueNAS server, then everything works perfectly.

So if the TrueNas app works fine on its own when accessed directly, that points to the router being the cause. But the same router doesn’t cause any issues when pointing to PiHole running on the raspberry pi!

What could be causing this issue? How can I troubleshoot it? Any help would be appreciated.

2

Without knowing info about your router, I think it’s about the limitations of PiHole running in a container or perhaps your router.

When I first installed the official truenas app, the proprietary router from my ISP would not recognize the ip address of the PiHole app at all. The work around was to configure the DNS settings of each client in my home network to the PiHole ip address. Later on, I wanted to use Unbound with PiHole but this does not work inside the app container in Dragonfish, don’t know about EE. So I installed a second instance of PiHole running on Ubuntu server inside a truenas VM. The VM PiHole seems to have a little more functionality and connectivity with websites.

So the solution for me is to configure the DNS settings of each client and go with what works on my home network. Oh, and don’t even try to run the PiHole app as the DHCP server.

3

Thanks for your answer. I think I might actually have figured it out.

The raspberry pi used to be on a static IP oustide of the router’s DHCP range while the TrueNas server was set up with a DHCP reservation. It seems like the router (Netgear R6800 with stock firmware) doesn’t like forwarding DNS requests within its DHCP range.

I set the TrueNas server on a static IP ouside de router’s DHCP range. Since then, there are no more DNS timeouts when devices get their DNS through DHCP from the router :slight_smile: