Authentication failing for one user group but not others? Here’s how I narrow it down

I am George Fady, I am a technical support engineer in Sangfor.

IAG’s authentication function verifies the identity of users accessing the internet through the device, and it’s the foundation that traffic management, access policies, and auditing all build on. When one group can’t authenticate while everyone else is fine, I don’t start with the authentication server
- I start with the group/user structure itself.

My checklist: confirm which authentication type that group is actually assigned (open authentication is not the same as the others, and a group can be silently misassigned);
check whether the group was added correctly under Access Mgt > Local Users, including whether it’s nested inside another group in a way that changes inherited settings;
and confirm user logout behavior isn’t the actual symptom being misreported as a login failure. A huge number of “authentication is broken” tickets turn out to be a user/group structure issue, not an authentication server issue.

Question for the community: what’s the most surprising root cause you’ve found behind an authentication ticket that initially looked like a server-side problem?

Thanks for sharing!