That’s done the trick, thanks for pointing me in the right direction.
I can see from the other thread the OP never responded to your last question about confirming what was done.
For me I simply did the following…
nano /etc/unbound/unbound.conf.d/plex.conf
Then added…
private-domain: "plex.direct"
Then restarted all services using dietpi-services, no need to reboot.
Cheers.