I use a Motorola myself, although a different model. Motorola Surfboard modems usually do not have any firewall, or much in the way of configuration outside what the ISP does. They do not need any ports to be opened. They are just a dumb modem and all data is passed through them unimpeded. I don't know where you found that information Alex, but going straight to Motorola, the data sheet makes no mention of any additional functionality above what a Surfboard usually has. See
http://www.arrisi.com/modems/datasheet/SB6141/SB6141_Data_Sheet.pdf The Surfboard IP address is usually 192.168.100.1 if you wish to check it out. You will see some settings on the Configuration screen, but unless you know what you are doing, leave them alone. A router's external IP address is never going to be in the range 192.168.xxx.xxx unless it is behind another NAT router. The internal address of the Linksys E1500 is 192.168.1.1. This is exactly the same setup I have at home.
I think you need to test if you can connect Gizmo to MC while both are connected on your LAN, before checking the WAN connection further. I don't have an Android device so haven't set up Gizmo. I've only used WebGizmo. But Gizmo uses the Access key the same way.
Is your Android device a phone or tablet? Does it have a cell phone data plan as well as Wi-Fi? If your Android device has Wi-Fi and can connect to your LAN, try turning off your cell data and just leave the Wi-Fi connection on, then test that you still have internet access on the device, then try to connect Gizmo to MC. Gizmo should be able to use the Wi-Fi connection and your MC Access Key to find the internal IP address of your MC PC and connect to it. (The Access Key method checks both your external and internal IP address when trying to connect.)
Did it work? If not, is the Commodo firewall still turned off? Turn it off and try again if so. Testing this way is not using the WAN connection of the router, so you are just testing your Gizmo installation and the MC PC setup. It should work. If it doesn't you need to go back and make sure you installed Gizmo correctly, following all the steps in the Wiki article.
http://wiki.jriver.com/index.php/Gizmo#Installing_GizmoIf it worked then turn off Wi-Fi on your Android device, turn on cell data, ensuring that your router will see a connection coming from the internet only, and not on the LAN. Then go into your router setup and make sure that logging is turned on (Enabled) and select "Incoming Log", as per the manual. Leave the log page open and try to connect with Gizmo. You may need to refresh the page to see the attempted connection, I can't tell from the manual. You should see a connection attempt from an external IP address, with the port number 52199. So, was the connection rejected or accepted?
Let us know what you found if you get this far.