CNAME record not working?

[FNorp93]

I'm trying to set up a domain for my NextCloud server with a reverse proxy.

So I set up a CNAME record of nextcloud.mydomain.me, pointed it to myserver.duckdns.org which constantly updates my WAN IP, and I configured the settings accordingly, but whenever I try to connect to my NextCloud page, it says it couldn't connect. The reverse proxy (letsencrypt) returns this error:

Obtaining a new certificate
Performing the following challenges:
http-01 challenge for nextcloud.(...)htower.me
Waiting for verification...
Challenge failed for domain nextcloud.(...)htower.me

http-01 challenge for nextcloud.(...)htower.me
Cleaning up challenges
Some challenges have failed.

IMPORTANT NOTES:
- The following errors were reported by the server:

Domain: nextcloud.(...)htower.me
Type: dns
Detail: DNS problem: NXDOMAIN looking up A for
nextcloud.(...)htower.me - check that a DNS record exists for this


ERROR: Cert does not exist! Please see the validation error above. The issue may be due to incorrect dns or port forwarding settings. Please fix your settings and recreate the container

As seen here, everything should be working fine:

Is there anything I should be doing? How do I get my NextCloud domain working?

[Nate · Accepted solution]

The host/name should just be "nextcloud", no need to add your domain in there.