The CCcam software is only created to work through internet.
Your Mvision 300 can act as a Client, but never as server.
In case you need a C line to define on your server configuration option, you need to contact a Server provider of a sharing Cccam line.
You have to configuer your IP and create a sharing port in your router.
Sorry, but he talked about a mvision HD300 combo and not about a HD300 combo NET.
The HD300 combo doesn't have an Ethernet LAN connection only a RS232 port.
That's why he probably wanted to know about the rs232 adapter.
Your box has got a ethernet connection, so in this case you got an internet or LAN connection.
You have to create a shared port in your router. Your Mvision will have also a IP address.
You have to define it on Accessory/Network.
On Network click on Type, and put it on ON.
Then you have access to Network, IP setup
Put Network setting on " manual " and define the IP detalis.
The gateway is the IP address of your router. 1st DNS is exactly de same as gateway.
Click on " apply ".
You should already plugged an ethernet cable between a port of your router en de Mvision ethernet port.
You are ready with your connection to internet.
Then you should have to get a C line from a CCcam server with the details:
IP of network received name. ????
Your shared port : ?????
and the provided password. ????
On this way you can connect to a server somewhere which will share a card with you.