TCP Port 44818 is the correct port for the Allen-Bradley "EtherNet/IP" protocol that the MicroLogix 1400 uses.
The "EtherNet/IP" driver in RSLinx Classic, however, uses a broadcast packet to detect devices. That obviously won't work over the Internet.
The "Ethernet Devices" driver in RSLinx Classic tries TCP Port 2222 first, to determine if the target device is an old PLC-5E or SLC-5/05. If it gets three "Port Closed" responses in a row, it will switch to trying TCP Port 44818.
Many VPNs and routers will block the TCP Port 2222 connection attempt, assuming it's some sort of port scan attack.
The easy solution is to append ":EIP" to the end of the IP address or hostname in the Ethernet Devices node list. This causes RSLinx to skip the TCP Port 2222 step.
Try using the
TCPING utility to connect to Port 44818 over your internet connection to the site. If TCPing works, RSLinx should too.
I always very strongly recommend the use of a VPN for this sort of application, though I've had several bad experiences with D-Link equipment. Which model of router are you using ?