No Connection Could Be Made Because the Target Machine Actively Refused It

No connection could be made because the target machine actively refused it 127.0.0.1:3446

"Actively refused it" means that the host sent a reset instead of an ack when you tried to connect. It is therefore not a problem in your code. Either there is a firewall blocking the connection or the process that is hosting the service is not listening on that port. This may be because it is not running at all or because it is listening on a different port.

Once you start the process hosting your service, try netstat -anb (requires admin privileges) to verify that it is running and listening on the expected port.

update: On Linux you may need to do netstat -anp instead.

No connection could be made because the target machine actively refused it Golang

net.Listen("tcp", "localhost:12345") is listening on localhost and client is trying to connect by IP.

Try connecting client on localhost

net.Dial("tcp", "localhost:12345")

Or listen the server on 0.0.0.0

net.Listen("tcp", "0.0.0.0:12345")

Win Error 10061 No connection could be made because the target machine actively refused it

when I try to run the server and client on different computers I get an error on the clients end

That is because you are using127.0.0.1 on both sides. That is the localhost loopback IP address. It works when the client and server are on the same machine, but it is not routable on the LAN network.

You need to:

change the server to listen on either 0.0.0.0 (to listen on all installed network interfaces), or its actual LAN IP address (just the network interface attached to the LAN).
change the client to connect to the server's hostname or IP address on the LAN.

I have tried changing the port multiple times but it didn't help

The problem is nit with the port, but with the IP address.

No connection could be made because the target machine actively refused it Nethereum exception

My problem turned out to be that I had initialised the Web3() with no parameters, so it defaults to using localhost as the RPC client. I fixed it by initialising it with the RPC client url that I needed, in this case:

string rpcClient = "https://bsc-dataseed.binance.org/";
Web3 web3 = new Web3(rpcClient);

No connection could be made because the target machine actively refused it. [tcp://127.0.0.1:6037]

The redis server was not started and the port number was wrong in my env file