The issue I am facing: I can manually configure my devices to use Pi-hole as DNS server (on iPhone, WIndows laptop, Linux laptop etc.). And all works well. But when I set my router DNS to be Pi-hole DNS, nothing works any more. I can change router DNS to be e.g. 1.1.1.1 or 8.8.8.8 and all works well. I can also test that DNS really changes when I change router settings.
Details about my system: Pi-hole is on Raspberry Pi 3 which is on local network. My router is Nokia Beacon
What I have changed since installing Pi-hole: Nothing
Is this a new router / new setup? Has it worked before but just stopped?
I recall issues with some routers will not allow a local DNS Server Address for security sake. I can't for the life of me remember the specific term. I seem to recall in those cases the router would not even take the local IP in the setting.
I would suggest posting the results of a dig / nslookup from a client with both the piholle set as DNS in the router and with 1.1.1.1 or 8.8.8.8.
You may also want to upload a debug file ( tool>generate debug log ) and post the link. A developer or moderator will like want to look at it.
Router and local network is "old", but Raspberry Pi with Pi-hole is newly added.
After some tests made, I found the "solution". So, I will leave it here if anyone has same problem.
I need to switch off Pi-hole, set router DNS as “non Pi-hole DNS” e.g. 1.1.1.1 and restart router (off/on). All works well, but of course without Pi-hole. Then I switch on Pi-hole and set router DNS to be Pi-hole DNS. Ta-da... All works well, with Pi-hole.
If now I switch off/on Pi-hole, it will work well again. But if I switch off/on router with Pi-hole set as DNS, system will not work, network devices cannot go to internet as DNS cannot find web sited addresses.
For me this solves the issue, so I will not investigate more, for now…