Just a note as I encountered this same issue from personal Windows 7 and 10 PC’s on successful install of the Epicor Client Software, but I did find a fix as well.
2 things fixed the login issue:
- Add both the \ERP server to windows hosts file (located at: %SystemRoot%\System32\drivers\etc\hosts) like this:
erp 10.0.0.1
erp.domain.com 10.0.0.1 - Use Credentials Manager in Control Panel to add domain user (not erp username) credentials to the workstation/pc for both FQDN (erp.domain.com) and HOST (erp)
This quickly resolved any problems with login failures.