| Gather Clues | |
| A. | Ask Questions. i. What were you doing when the problem occurred? ii. Have there been any recent changes to the network? |
| B. | Have the customer recreate the problem while you watch. While watching, check for obvious user errors (ID10T errors), such as Caps-Lock being on. |
| Possible Solutions | |
| A. | Specific service is down on destination server. The server itself is up and communicating, but the specific service you are trying to access is down for some reason. Figure out why the service is down (look at configuration, recent updates, & logs), and bring it back up. If it is still up but not responding, restart it. |
| B. | Misconfigured firewall. Network firewall may be blocking all access from your LAN to specific service port on destination server. Configure it to allow your LAN access to service. |
| C. | Malware infection on destination server or it has been hacked. Scan server for malware infection using anti-malware software such as MalwareBytes. Check for signs of break-in (look at the logs). |
| If All Else Fails | |
| A. | Sniff the network with Wireshark on the server while recreating the problem. See if packets are actually being sent to the correct port and if there are any replies. Look for packets containing diagnostic or error messages. |
| B. | Search the Internet. See if others have had the same problem, and if so, how they solved it. |