There is no specific limit set by EEG on how many networks an Alta VM can be connected to. You may be restricted by the number of physical networking ports on your host machine, or by the number supported by your virtualization software per VM.
It is possible to run all Alta-related functions (receive & transmit of media streams, web-based management, outbound connections to iCap/Lexi, and licensing validation) through a single network interface (NIC). It is also possible to divide these functions for reasons including increased bandwidth for media streams, QoS, and security separation of outbound iCap traffic and media networks.
The Alta VM will have a separate IP address for each separate network it is connected to.
The network for outbound iCap traffic should usually go through eth0 or the "first" network adapter if possible. This will prevent you from having to re-configure a different adapter as the "default route" for outbound traffic out of your local subnets.
For multicast media streams, use the "Multicast Interface" setting on each stream to set the IP address that for media transmit/receive.
For unicast media stream reception, provide the IP address of the interface to receive the stream on in the "input" field of the Alta channel. If only a port number is provided, unicast streams will be received across all interfaces on that port (and you must not send multiple unicast streams on the same port, even to different interfaces). For unicast stream transmission, the lowest numbered interface with a subnet matching the destination will be used (unless a different default route is set up in the Alta underlying Linux system).