I'm running SQL Express in a small environment. The server is also the domain controller running Hyper V, SQL Server Express is running on a Win 10 guest. SQL Server connects on several existing workstations without problems. When adding a new workstation, i receive the certificate chain was issued by an authority that is not trusted error. I looked at the certificates and see no missing certs. This only occurs on new workstations.
(2) Please clarify that I understand the scenario correctly
You can connect from some workstations without problems but now that add another one then you have issue. Right? In this case, can you try to check if you find the differences with the network and user/login configuration