WWW CNAME

Just transferred our domain to SS from Ionos.  Reading through the docs & reviewing the various posts about the SS CNAMES, our CNAME records work except for the www record.  Our www CNAME record points to the root domain so my question is:  When I created the CNAME record for www, I entered www for the host field and the domain.com for the data field.  I cannot get the www.domain.com to find the website that worked with Ionos but now here with SS.  If I run a nslookup www.domain.com, it returns the correct information.  Is there a step I have missed?

Sorry, forgot to post some of the relevant information to conform to the forum guidelines:

URL for the domain address is jcasvcs.com.

Domain is hosted by SS.

Website is hosted on our Ubuntu 24.04 server with Nginx as the frontend.

Website is published & was working fully as www.jcasvcs.com before moving from Ionos.

I can reach your site with the www and without, but it is not secure. I could not find an SSL certificate for your domain. 

https://www.sslshopper.com/ssl-checker.html#hostname=jcasvcs.com

3 minutes ago, derricksrandomviews said:

I can reach your site with the www and without, but it is not secure. I could not find an SSL certificate for your domain. 

https://www.sslshopper.com/ssl-checker.html#hostname=jcasvcs.com

Interesting.  The only way I am able to test is using the data on my mobile phone which fails to connect using the www prefix.  As for SSL, I understood that the SS domain comes with one but I haven't gotten to the point of applying it to the website.  I just needed the website connection for a payment processor to verify.  I actually have no need for a website but the payment processor requires one....go figure.  SSL will be forthcoming sometime.  Thanks for your help in verifying this..

You are welcome.