Having an issue in which your TransPort WR21 2-port, WR44, etc., does not respond on an Ethernet port? Check to see whether Port Isolation is enabled. You may need to be in Hub mode. To understand what "Port Isolation" and "Hub Mode" are, please reference the Digi TransPort User's Guide.
In the WebUI, go to Configuration - Network > Interfaces > Ethernet > ETH 0 > Advanced. The second line should tell you whether it is in Port Isolate or Hub mode.
Likewise, you can see this under Configuration - Network > Interfaces > Ethernet > ETH 1 > Advanced.
If it is in Port Isolate mode, simply click the button to place it into Hub mode.
FYI – resetting to factory default will NOT change it back to Hub Mode. This setting is stored internally, not in config.da0.