DDS (Data Distribution Service) and RTPS (Real-Time Publish Subscribe) are good candidate technologies for the Industrial Internet of Things (IIoT). However, the discovery protocols in RTPS assume that the underlying network supports multicast and that datagrams are not subject to network address translation (NAT). Both of these assumptions are violated in a typical IIoT application. This article presents a solution to these problems by introducing a service that relays RTPS messages.