I have setup Windows NLB which works fine with http. But it is not forwarding the UDP reply to the client.



Host1 -

Client -

I am forward all the ports including UDP and TCP protocols.

nlb port rules

But through an application (from client) I send bytes to the and it has reached to the Host1( I could see the logs.

But the reply message which has sent from the Host1 is not reaching the client.

On an other try I run the same application targeting to the Host1 directly without NLB.

The full duplex communication was fine. Client and Host1 could exchanging messages via UDP directly but Windows NLB could not do it so?


When using NLB, the server doesn't send UDP packets from the NLB address. So if your client is expecting a packet back from, it won't work because the UDP packet will come from

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.