Expected Behaviour:
I'm trying to block ads using pihole... I've added (\.|^)amazon-adsystem\.com$ to block ads coming from all sub-domains of amazon-adsystem.com
I've flushed pihole cache and even restarted the service :
# pihole reloaddns
[✓] Flushing DNS cache
# systemctl restart pihole-FTL.service
However, queries to subdomains are still forwarded and replied to.
I'm running on a Raspberry Pi 4, all clients get IP via DHCP on pihole, and dns server is set to the pihole.
pihole -d uploaded = https://tricorder.pi-hole.net/VVSUG3qd/
I have 25+ years of DDI experience, and I'm lost... pihole simply isn't blocking 
The debug log shows your settings are correct, but you disabled the Default group:
*** [ DIAGNOSING ]: Groups
id enabled name date_added date_modified description
---- ------- -------------------------------------------------- ------------------- ------------------- --------------------------------------------------
0 no Default 2026-06-01 16:32:30 2026-09-16 11:42:33 The default group
When a group is disabled, all lists, domains and regex rules assigned to this group are also disabled.
Solution:
Enable the Default group.
Absolutely spot on, thanks so much!!
Weird as this was a new install (I've done a few now) and I hadn't changed that setting.
Anyway, all sorted now, much appreciated 