Custom ports do not work on 4G mobile hotspots. All attempts to route your connections out anything but the default ports will be blocked by the VZW NAT firewall.
This is a common limitation to the new SIM card network that did not exist on the old 3G devices. Webcams, VOIP phones, XBox Live, etc. Basically anything that needs a Public IP address or service will not be available to you on the new network.
The only work arounds are to experiment with VPN's or purchase a public IP address from VZW for a few hundered dollars. There are a number of free VPN services available