If you purchased a SmartServer IoT PRO EX (model number 72201R-248 and previously called SmartServer IOT PRO WiFi) and you don't see the RS-485 menu show up in the SmartServer Configuration pages (where you see System and Network pages) then you need to run the following workaround.
ssh or console into the SmartServer and run the following two commands
sudo fw_setenv echelon_rs485a 1
sudo fw_setenv echelon_rs485b 1
If you still don't see the RS-485 menu in the Configuration Web page then reboot the SmartServer.