Обмен данными по TCP с устройством - зависает при приёме

Imports System.Net.Sockets
 
Public Class Form1
    Dim tc As TcpClient
 
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        TextBox2.Text = ""
 
        Dim parts As String() = TextBox1.Text.Split(" ")
        Dim bytes(parts.Length) As Byte
 
        For i As Integer = 0 To parts.Length - 1
            bytes(i) = Convert.ToByte(parts(i), 16)
        Next
        tc = New TcpClient("192.168.1.78", 23)
        Dim ns As NetworkStream = tc.GetStream()
 
        ns.Write(bytes, 0, bytes.Length)
 
        Dim read_bytes(50) As Byte
        ns.Read(read_bytes, 0, read_bytes.Length)
        ns.Flush()
        ns.Close()
 
        For f = 0 To 26
            TextBox2.Text &= h_Hex(read_bytes(f))
        Next
 
    End Sub
    Public Function h_Hex(Text As String) As String
        If Len(Text) = 0 Then Exit Function
 
        If (Len(Hex(Text)) Mod 2) Then
            h_Hex = "0" & Hex(Text) & " "
        Else
            h_Hex = Hex(Text) & " "
        End If
 
#Disable Warning BC42105 ' Функция не возвращает значение на всех путях к коду
    End Function
 
#Enable Warning BC42105 ' Функция не возвращает значение на всех путях к коду
 
End Class

ns.Read(read_bytes, 0, read_bytes.Length)

Public Class Form1
    Dim tc As TcpClient
 
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Try
        TextBox2.Text = ""
 
        Dim parts As String() = TextBox1.Text.Split(" ")
        Dim bytes(parts.Length) As Byte
 
        For i As Integer = 0 To parts.Length - 1
            bytes(i) = Convert.ToByte(parts(i), 16)
        Next
 
        If tc Is Nothing Then tc = New TcpClient("192.168.1.78", 23) '!!!!!!!!!
        Dim ns As NetworkStream = tc.GetStream()
 
        ns.Write(bytes, 0, bytes.Length)
 
        Dim read_bytes(50) As Byte
 
        ns.Read(read_bytes, 0, read_bytes.Length)
        ns.Flush()
        ns.Close()
 
        For f = 0 To 26
            TextBox2.Text &= h_Hex(read_bytes(f))
        Next
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

Dim ipEndPnt As New IPEndPoint(IPAddress.Parse("192.168.1.78"), 23)