Narrowing possibilities.
WHAT TO DETERMINE
Is it one user or many? One device or many? One application or all? One location or everywhere? Constant or intermittent?
WHAT EACH ANSWER ELIMINATES
- One user: profile, permissions or their device
- All users: a shared system
- One application: that application or its dependencies
- All applications: the system, network or platform
- One location: local network or infrastructure there
WHY THAT MATTERS
Each question halves the problem space.
WHAT TO TRY
Substitution: a different device, account, cable or network.
WHY SUBSTITUTION
It proves which component is involved, definitively.
WHAT TO WORK FROM
The bottom upward: physical, then addressing, then service.
WHY
A lower-layer fault makes everything above it fail.
WHAT TO CHANGE
One thing at a time, recording each.
WHAT TO DO IF A CHANGE DOES NOT HELP
Reverse it before trying the next.
WHY
Otherwise you accumulate changes nobody can account for.
