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I recently bought myself a new Synology NAS on which you can install and run Docker images.

One of the containers I'd like to run is pihole/pihole (v4). This appears to be working and from what I can see in the web portal (of both the NAS and PiHole) it's working properly. All requests I'm making (from a phone, laptop or desktop) appear to be resolved via PiHole.

There is however 1 major problem. It appears, even though the DNS requests are being made in PiHole, the responses aren't returned to my devices. When doing an nslookup or ping I'm not receiving any response.

D:\Temp>nslookup google.nl
DNS request timed out.
    timeout was 2 seconds.
Server:  UnKnown
Address:  192.168.1.158

DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to UnKnown timed-out

But as I already mentioned, I do see stuff getting resolved the PiHole portal.

2018-08-23 21:20:24     AAAA    google.nl   172.17.0.1  OK (forwarded)  N/A

There is a firewall present on the Synology, which was turned off. I've turned it on again and enabled a rule to Allow all traffic (which should be the same as turning it off). I also turned off my Windows Firewall, just to test stuff. Sadly, both solutions didn't help a bit.

I think my configuration is set up correctly, port 53 is being forwarded to port 53 in the container.

Docker port settings

Port 80 and 443 aren't set up correctly yet, but this shouldn't be an issue when resolving domains. Port 67 is used for DHCP, which I'm not handling in PiHole, so it shouldn't matter also.

The container is running in Bridge network mode which shouldn't pose any problem if the necessary ports are being forwarded correctly. Running the container in Host network mode didn't appear to be working either, probably because the public ports are assigned Auto ports in this mode.

For completeness sake, a screenshot of all my info service on the Synology. Info service

I had assumed port 53 should be shown on the Local Port column for the Docker entry. Maybe that's the problem, but I don't know how this has to be resolved. The Test Connection button appears not to do much either.

So my question is, what could be the problem my PiHole container is doing DNS requests for my devices, but the responses aren't being returned to any of my devices?

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1 Answer 1

Reset to default
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I've finaly managed to solve my timeout issue.

When navigating to the PiHole settings in the webportal, there's an option called Interface listening behavior.

This setting was set at the option Listen only on interface eth0. I've changed this to Listen on all interfaces and the problem appears to be solved on my machines. The option Listen on all interfaces, permit all origins also appears to work, but I'd rather not keep this option activated.

Also, I had to change the network from Bridged to Host. The port forwarding doesn't appear to work (properly) at the moment.

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  • I have opposite setup. Pihole on raspberry (in docker) in local network. Resolution was working fine in the whole network and wasn`t working from docker containers. Switching back to listen on eth0 interface solved the problem with docker. Your post help me to try switch that configs. Thank you.
    – Sedos
    Commented May 28, 2020 at 1:41

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