Cloudflare

Select the URL affected by the Server-Side :

Add a first entry with a "NS" pointing field using the subdomain you previously selected in your GTM (e.g., xyzxx) and the nameserver URL "ns1.gtm-helper.com"

Save

Type "NS", Name "xyzxxx", Nameserver "ns1.gtm-helper.com"

Repeat the operation a second time for the same subdomain, with the nameserver URL "ns2.gtm-helper.com"

Type "NS", Name "xyzxxx", Nameserver "ns2.gtm-helper.com"

Save