Hi @Viblio,
Thanks for reaching out and welcome to the Netlify Support Forums!
Visiting the site, I see you have a DNS Zone configured for viblio.com, however, it is inactive:
dig viblio.com NS +trace | tail -n 6
;; Received 732 bytes from 192.48.79.30#53(j.gtld-servers.net) in 14 ms
viblio.com. 1800 IN NS dns1.registrar-servers.com.
viblio.com. 1800 IN NS dns2.registrar-servers.com.
;; Received 95 bytes from 2610:a1:1025::200#53(dns2.registrar-servers.com) in 33 ms
We have a Support Guide on how to detect and fix a inactive DNS Zone here:
I do see that you have viblio.com and www.viblio.com configured for External DNS, so you can remove the inactive DNS Zone by following the solution here.
Please let us know when you’ve removed the inactive DNS zone and double-checked the Support Guide for configuring branch subdomains without Netlify DNS.