Here are some things you can check:
1. Check if the right NIC is being used.(If you have multiple network adapters)
Go to Common > Network Information and check the mac address to see if BA has selected the right nic. If not disable the selected NIC until it selects the right one. I haven't found a way to configure the nic it should use.
2. Check your network setup.
Livewire uses multicast, is your network configured to use multicast? If both devices are in the same broadcast domain(they have the same or no default gateway) network it's pretty straight forward and should just work. If however the devices are in different networks(they have a different default gateway) then you have make sure the network is setup for multicast routing.
3. Setup the source(studio):
Go to HD Processor(or watever the core is you use) > Misc > Livewire > Main Output
Choose a channel number, is used 1. And click enable
4. Setup the receiver(transmit site)
Go to Passthorugh(or watever the core is you use) > Misc > Livewire > Input
Choose the same channel you set at the source and it should start streaming.