Hi, never used cloudlare tunnel myself.
The main issue usually is incorrect DNS.
How do you access your device by IP or DNS?
IP would give you only admin web.
To access apps you need to use dns and it needs to be updated with correct IP (usually happens automatically). Device has two modes to operate local and external. Local will update dns records to device local IP for local lan usage. External will try to guess your external (oublic) IP and update dns with it (will sync every 15 mins for dynamic IPs).
I’m using DNS internally only. the cloudflare tunnel software is installed locally on another server in my network. but for some reason, the nextcloud subdomain is resolving to the server IP and not the app?
cloudflare is free for home users, and is a great alternative to not opening ports on home firewalls.