Try to add dns option to your compose file, like this:
services:
pihole:
container_name: pihole
image: pihole/pihole:latest
dns: 8.8.8.8
ports:
(...)
Then test again.
Try to add dns option to your compose file, like this:
services:
pihole:
container_name: pihole
image: pihole/pihole:latest
dns: 8.8.8.8
ports:
(...)
Then test again.