Help with certbot and ssl for use with subdomain and raspberrypi

Hello again comunity,

I have successfully installed Nextcloudpi on my Raspberrypi. I added a DNS A record to my dns manager to point to the IP address of my Raspberrypi (global static ip). So DNS A record points successfully to my.domain.com. Then I used certbot to create a SSL certificate

  • Congratulations! Your certificate and chain have been saved at:
    /etc/letsencrypt/live/my.******./fullchain.pem
    Your key file has been saved at:
    /etc/letsencrypt/live/my.
    ****./privkey.pem
    Your cert will expire on 2019-0
    -**. To obtain a new or tweaked
    version of this certificate in the future, simply run certbot again
    with the “certonly” option. To non-interactively renew all of
    your certificates, run “certbot renew”

but it seems that something doesn’t work right as when I check my url at www.ssllabs.com I get the following result


SSL Report: my.. (..***.***)
Assessed on: Thu, 29 Nov 2018 19:03:34 UTC | HIDDEN | Clear cache

Certificate name mismatch
Click here to ignore the mismatch and proceed with the tests

Try these other domain names (extracted from the certificates):

archlinux

What does this mean?

We were able to retrieve a certificate for this site, but the domain names listed in it do not match the domain name you requested us to inspect. It’s possible that:

The web site does not use SSL, but shares an IP address with some other site that does.
The web site no longer exists, yet the domain name still points to the old IP address, where some other site is now hosted.
The web site uses a content delivery network (CDN) that does not support SSL.
The domain name is an alias for a web site whose main name is different, but the alias was not included in the certificate by mistake. 

Of course when I try to access nextcloudpi via the domain name , I am redirected to the site getting the warning for the ssl certificate.

Any idea what I can try?

thanks!