fritex
2
Greetings,
Thank you for asking.
I am sorry to hear this.
Unfortunately, when I do a lookup for your erp sub-domain, I cannot find any A, AAAA or CNAME records:
Kindly, check the DNS tab of Cloudflare dashboard for your domain name and add the missing A erp pointed to your cPanel hosting IP address and proxied 
by following the instructions from the article below:
In case you encounter an issue or error related to the SSL, make sure to:
- Use the “Pause Cloudflare on Site” option from the Overview tab for your domain at dash.cloudflare.com .
- The link is in the lower right corner of that page.
- Give it five minutes to take effect
- Check for the valid SSL certificate for your sub-domain
- If not generated, start the renew process via cPanel AutoSSL / Let’s Encrypt / Certbot / ACME.
- Then make sure site is working as expected with HTTPS with a valid SSL certificate.
- Only then should you un-pause Cloudflare and double-check your SSL/TLS setting to make sure it’s
Full (Strict) → Why you should choose Full Strict, and only Full Strict .
And just in case, see below article:
Here is a way to re-check if you correctly setup the SSL for your domain with Cloudflare:
Have you got the access to manage your domain name at Cloudflare? 
Maybe the sub-domain was added as a part of SSL for Saas?