yes the password was the problem, I was trying to write a longer one, then trying without setting a password, thinking it would use the same one as for MEB
hope there would be a AMT/vPRO for dummies
also found that vnc procotol has a 8 bytes password limit, wish I'd known that beforehand
thx for sheding light
Sorry - deleted my oroginal response by mistake - here is recreated answer:
Intel AMT KVM RFB Standard port (5900) requires to be protected by RFB strong password.
It is exactly 8 characters (not 7 or less neither 9 or more!).
This password has to be configured into AMT FW to allow enabling RFB Standard port (via Intel SCS, Host Based Configuration or other AMT tools).
Setting RFB Standard port password and enabling RFB Standard port requires AMT PT Administration ACL realm (AMT administrator access).
Uppon RFB Viewer app connection over RFB standard port user will be asked to provide this RFB Standard Port password -but nothing else!.
RFB Standard port access is NOT encrypted neither protected with AMT access credentials (digest /AD Kerberos) so it is not recommended to be setup/used in enterprises.
Good for POC/Small pilot but not for production environment.