When Industrial IoT was first introduced, companies turned to familiar protocols like OPC UA and MQTT to make connections. But those protocols were designed 20 years ago, long before the IIoT was requiring secure, robust connections across insecure networks. This white paper explains the strengths and weaknesses OPC UA, MQTT, and other protocols for IIoT, and introduces Skkynet’s DHTP (DataHub Transfer Protocol) for comparison.