ssl-vg03.vgwort-de.2cnt.net appears to be a subdomain linked to a tracking service, but it's not functioning properly. The biggest issue is an invalid SSL certificate, which means any data sent to or from this server is at risk. For a site that's likely used to collect analytics or confirm page views, that's a significant failure. There's also no public record of who operates it, and no privacy policy or terms of service are in place. While the domain isn't blacklisted and Google hasn't flagged it as malicious, the combination of a broken certificate, no contact information, and no legal pages makes it impossible to recommend. If you're asked to load this domain (for example, as a tracking pixel), you should question whether it's properly configured. Without a valid SSL certificate, is ssl-vg03.vgwort-de.2cnt.net safe? Not right now. The only way to trust it would be to see the SSL issue resolved and basic compliance documents published.