Pihole server is running on an Intel NUC running Ubuntu 18.04 headless. Server indicates pihole is running with no problem:
[✓] DNS service is running
[✓] Pi-hole blocking is Enabled
Expected Behaviour:
Internet traffic being "routed" through pihole, with query logs shown in web admin interface.
Actual Behaviour:
No query logs shown in web admin interface.
No internet traffic for any of the clients if I use pihole server as my DNS.
Yes, Pihole is my only DNS. And if I set pihole as my sole DNS, I will have no internet traffic on any of my clients. I suppose the issue is not with "leakage," but actual domain name resolve functionality.
I see you are running on Ubuntu 18.04 there are several known issues with Netwrork Manager in that OS this post has a lot more detail and some steps to try