Unable to connect second node to seed node – “Couldn’t connect to the seed node on port 4419”

Question

Hi,

I’m currently setting up a MultiChain network (version 2.3.3 – protocol 20013) and facing an issue while connecting a secondary node to the seed node.

When I run the following command on the secondary node:

multichaind [chain-name]@[seed-node-ip]:[port-number] -datadir="E:\Multichain\nodes\SecondNode" -daemon

I receive this error:

Retrieving blockchain parameters from the seed node [seed-node-ip]:[port-number] ... Error: Couldn't connect to the seed node [seed-node-ip] on port [port-number] - please check multichaind is running at that address and that your firewall settings allow incoming connections.

Here are my setup details for context:

• MultiChain version: 2.3.3 (Community Edition, protocol 20013)

• Seed node IP: [seed-node-ip]

• Port configuration: default-network-port = [port-number], default-rpc-port = [rpc-port]

• OS: Windows Server on both nodes

• Telnet test: Successful on port [port-number]

• multichain.conf on seed node:

  rpcbind=0.0.0.0 rpcallowip=0.0.0.0/0

• Firewall: Port [port-number] opened for inbound/outbound TCP

Despite these settings, the secondary node still cannot connect.

Could you please help me identify what might be causing this connection failure?
Do I need to modify any additional parameters (such as bind, externalip, or interface configurations) for Windows environments?

Thank you in advance for your assistance.

Answer 1

The most common issue is getting the RPC port and the network port mixed up.

When you started the first node, it should show you the multichaind command to run on a second node in order to connect to it. This command includes the network port, rather than the RPC port.

Could you please check this is the command you are using?

If so, please output the response when you telnet to that port (from the second server, presumably).

Comments

I've used both the ports, still the same issue.

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OK. Can you show the output of telnet when you connect from the first server to the network port on the second server?

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From the secondary node:

C:\Windows\system32>netstat -ano | find "<network-port>"

C:\Windows\system32>powershell -Command "Start-Job { while ($true) { $client = (New-Object System.Net.Sockets.TcpListener(<network-port>)); $client.Start(); $client.AcceptTcpClient(); $client.Stop(); } }"

Id  Name  PSJobTypeName  State    HasMoreData  Location
--  ----  --------------  -----   ------------  --------
1   Job1  BackgroundJob   Running True         localhost

C:\Windows\system32>netsh advfirewall firewall add rule name="Multichain-NetworkPort" dir=in action=allow protocol=TCP localport=<network-port>
Ok.

C:\Windows\system32>netsh advfirewall firewall add rule name="Multichain-NetworkPort-out" dir=out action=allow protocol=TCP localport=<network-port>
Ok.

From the primary node:

E:\Multichain\multichain-windows>telnet <secondary-node> <network-port>
Connecting to <secondary-node>...Could not open connection to the host: Connect failed

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So telnet was not successful?

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Telnet is successful now, but still the same issue.

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Problem:
After setting up a Multichain network, nodes were unable to connect to the primary node. The issue was caused by a configuration in the multichain.conf file that limited the maximum number of peer-to-peer (P2P) connections to just 10. As a result, each node required 32 connections to connect properly, but the limit prevented successful communication.

Cause:
The maxconnections=10 setting in the multichain.conf file restricted the number of allowed peer-to-peer connections, preventing the node from establishing a sufficient number of connections to the primary node.

Solution:
To resolve this issue, remove or comment out the maxconnections=10 line in the multichain.conf file. This will remove the connection limit, allowing the nodes to connect as needed.

# === NETWORK / P2P ===
# maxconnections=10         # Max number of peer-to-peer connections (adjust based on network topology)

After removing this line, the nodes successfully connected to the primary node, and the network issue was resolved.