Troubleshooting
Network Troubleshooting
Network Troubleshooting in industrial control systems — covering 6 topic areas in the CurryControls.com controls and automation knowledge hub.
Written guides in this section
Full references, procedures, and diagnostic guides published under Network Troubleshooting.
Intermittent Packet Loss
Polls that occasionally fail, tags that flicker bad, a ping that drops one in fifty: a bad cable or port, a duplex mismatch, a saturated link, a buffer overrun, a marginal radio or fiber hop, a slow device, or a loop. Finding which hop loses packets and why.
9 min readUpdated Sep 5, 2026
Cannot Ping Across VLANs
Two devices that work on their own networks but cannot reach each other across a VLAN boundary: no route, a wrong or missing gateway, a mask that puts the target on the wrong side, a trunk missing the VLAN, or a firewall rule. Testing each in order.
8 min readUpdated Sep 5, 2026
Duplicate IP Address
Two devices claiming one address: a controller that answers sometimes, a workstation that reports a conflict, a ping returning from two hardware addresses. Where duplicates come from, finding both in the switch address table, and the discipline that stops it.
7 min readUpdated Sep 5, 2026
Switch Port Errors Incrementing
What each counter on a managed switch port means and which fault makes it grow: check errors from a damaged cable or noise, late collisions from a duplex mismatch, runts from a bad transceiver, discards from congestion, link flaps from a marginal connection.
9 min readUpdated Sep 5, 2026
Broadcast Storm
A network suddenly slow or dead everywhere, every link light solid: a loop between switches without protection, a failed ring protocol, or a device flooding broadcasts. Recognising a storm, breaking it with a cable pull, finding the loop, and preventing it.
8 min readUpdated Sep 5, 2026
Ethernet Device Drops Offline
An industrial Ethernet device that disappears and comes back. Duplex mismatch, cabling, spanning tree, and the switch counters that identify it in minutes.
9 min readUpdated Aug 16, 2026
Topics in this area
Ethernet Device Drops Offline
Duplex mismatch, cabling, spanning tree, and the switch counters that give it away.
Intermittent Packet Loss
Intermittent Packet Loss — practical reference notes for controls engineers, integrators, and technicians working with network troubleshooting.
Cannot Ping Across VLANs
Cannot Ping Across VLANs — practical reference notes for controls engineers, integrators, and technicians working with network troubleshooting.
Duplicate IP Address
Duplicate IP Address — practical reference notes for controls engineers, integrators, and technicians working with network troubleshooting.
Switch Port Errors Incrementing
Switch Port Errors Incrementing — practical reference notes for controls engineers, integrators, and technicians working with network troubleshooting.
Broadcast Storm
Broadcast Storm — practical reference notes for controls engineers, integrators, and technicians working with network troubleshooting.
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