I use Spark 2.8.3 on Windows 7 Pro 64-bit. I have 3 usera who cannot login. It says can’t connect to server: invalid name or server not reachable. I have 12 other users who are able to login just fine.
Do you put the same thing as a Domain on both working an not working computers/users? Is it a name or IP? Maybe those computers which can’t find the server are in a different network subnet, wifi, have firewall blocking the connection. There should be something different about them or a network they are working in.