403 return code only from specific IPs


we are currently facing problems fetching any modules from public terraform registry. This is most likely related to a pure networking issue on the terraform registry side. We only experience this when we connect from specific public IP addresses on our end (big public cloud provider). A simple $ curl -I https://registry.terraform.io results in a 403 sent from a Varnish server. Is there a way to check on Hashicorp’s end whether certain IPs are blacklisted?

Best regards