Pi-hole client local domain name not updating

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Expected Behaviour:


I’ve recently set up a pi-hole which has been working great on my Rasberry Pi 3B+.

I decided to change the local domain name ‘localdomain’ to ‘lan’ on the Pi-hole, and my DHCP server on my Ubqiuity USG. The GUI fails to update the old clients local domain name and only new clients reflect the local domain change.

I have verified the local domain update is working by pinging the clients with new local domain.

I have restarted DNS resolver, restarted the pi-hole, and flushed the logs.

I believe that there is possibly a file cache of the clients that need to be cleared in order the client list name to be updated. Any suggestions for resolving this would be appreciated.