NTFY (Notify) through tunnel

I am using Cloudflared in a Docker environment on Raspberry Pi. I use Zero Trust to manage the access to the applications through a tunnel. On computers I use Warp. On conputers all is fine, no issues at all. I have trouble with my notification server NTFY running in a Docker container. NTFY works fine using a computer but I can’t use it on my phone. This is my docker-compose configuration for NTFY:

ntfy:
image: binwiederhier/ntfy
container_name: ntfy
command:
- serve
environment:
- TZ=$MY_TIME_ZONE
- NTFY_BEHIND_PROXY:true
- NTFY_LISTEN_HTTP=:7777
- NTFY_BASE_URL=http://ntfy.mydomain.be
- NTFY_AUTH_DEFAULT_ACCESS:deny-all
- NTFY_ENABLE_LOGIN:true
- NTFY_UPSTRAM_BASE_URL=http://ntfy.mydomain.be
volumes:
- /home/pi/docker/ntfy/cache:/var/cache/ntfy
- /home/pi/docker/ntfy/config:/etc/ntfy
ports:
- 7777:7777
healthcheck:
test: [“CMD-SHELL”, “wget -q --tries=1 http://localhost:7777/v1/health -O - | grep -Eo ‘"healthy"\s*:\s*true’ || exit 1”]
interval: 60s
timeout: 10s
retries: 3
start_period: 40s
restart: unless-stopped

On the phone I installed 1.1.1.1 by Cloudflare. After entering the credentials the app remains in the state of reconnecting, no chance to get any notification. What could be the issue??

I really appreciate some help.