0. Download and install adb (Android Debug Bridge) and if you have a Mac, install the Horndis tethering driver for MacOS
1. Plug your stick to your Mac/PC and enter the following url in your browser:
192.168.0.1/goform/goform_set_cmd_process?goformId=USB_MODE_SWITCH&usb_mode=6
You will get: {"result":"success"}
2. Open the Terminal/Cmd and test the connection with adb shell. If you get the shell, type exit
3. Download the menu.js from the stick:
adb pull /usr/zte_web/web/js/config/datacard/mf831/menu.js
4. Make a backup copy from menu.js.
5. Edit the menu.js and add the following objects after the "#pin_management":

		 {  
		 hash:'#port_forward',  
		 path:'firewall/port_forward',  
		 level:'3',  
		 parent:'#device_setting',  
		 requireLogin:false,  
		 checkSIMStatus:false  
		 },  
		 {  
		  hash:'#router_setting',  
		  path:'adm/lan',  
		  level:'3',  
		  parent:'#device_setting',  
		  requireLogin:false,  
		  checkSIMStatus:false  
		  },  
		 {  
		 hash:'#dmz_setting',  
		 path:'firewall/dmz_setting',  
		 level:'3',  
		 parent:'#device_setting',  
		 requireLogin:false,  
		 checkSIMStatus:false  
		 },  
		 {  
		 hash:'#upnp_setting',  
		 path:'firewall/upnp_setting',  
		 level:'3',  
		 parent:'#device_setting',  
		 requireLogin:false,  
		 checkSIMStatus:false  
								 },  
		 {  
		 hash:'#port_filter',  
		 path:'firewall/port_filter',  
		 level:'3',  
		 parent:'#device_setting',  
		 requireLogin:false,  
		 checkSIMStatus:false  
		 },

6. Upload the modified menu.js with
adb push menu.js /usr/zte_web/web/js/config/datacard/mf831/
7. Test the web interface on 192.168.0.1

Screenshots: