In the first example above the consensus client can connect to Nethermind on the port 8551 if the consensus client is on the same machine. JsonRpc for other things is available at port 8545 on the same machine.
If you want to use a consensus client that's on a different machine, you can add the JsonRpc.EngineHost parameter and use 0.0.0.0 like the second example above. This will expose the JsonRpc.Engine to the outside.
if you want to changeJsonRpc.EngineHost, JsonRpc.EnginePort should be specified as well.