Pi-hole blocking internet access for whole network

[deHakkelaar]

Have you setup the router DHCP service like described in that doc I posted earlier ?
If not and configured the WAN/Internet DNS settings to point to Pi-hole, you might experience some kind of router security feature like rebind protection that DanSchaper mentioned earlier:

Why won't Pi-hole work with DNS rebind protection enabled?

What is DNS rebind protection? If your router has an option called DNS rebind protection enabled, you may run into issues when trying to use Pi-hole as your DNS server. The reasons for this are quite technical, but to summarize what this option does in one sentence: DNS rebind protection does not allow DNS queries to be answered with a local IP address. Why does this interfere with Pi-hole? DNS rebind is meant to be a countermeasure to an attack on your network. So in many cases, it's actu…

The end goal is to have a response similar as below on a client:

C:\>nslookup pi.hole
Server:  ph5
Address:  10.0.0.4

Name:    pi.hole
Address:  10.0.0.4

---

C:\>nslookup flurry.com
Server:  ph5
Address:  10.0.0.4

Name:    flurry.com
Addresses:  ::
          0.0.0.0

EDIT: Dont run nslookup in a Termux session on Android!
Termux always default uses Google's public DNS service at 8.8.8.8 if not specify a DNS server.
For Android you can install the "Network Info" app that up till now reliably shows DNS servers configured.