listener.BeginGetContext and System.Net.Sockets.TclClient

I have an application that listens on multiple context listeners.

When I get a request on a listening, I get the Data Received and then write
it on a socket to another server and read the socket looking for a response.

Everything is working, except that when reading and waiting for a response,
it blocks any new listener request from being fired for BeginGetContext and I
can not figure out why this is happening? As soon as the read returns the
BeginGetContext works normally.

How can I troubleshoot this? What can I see if and how the socket read is
blocking the next listener from firing?

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SteveS