app.run(debug=False)

If there's no need for python3, again, I recommend the impacket library. Here you can find a working ui example. Just make sure that impacket and ntpath.py is installed.
If you like to go further with pysmb, then you find more information in the Microsoft openspecs of SMB2 (Connecting to a Share by Using an SMB2 Negotiate, Message Syntax and SMB2 Packet Header - SYNC). Good luck!

The SMB dialect negotiation is always good, but the authentication fails in my case. Don't know if SMB signing deativated is okay... it is always deactivated with my smal travel router. So if you like you can check the base.py file and log the output.

Mmmh, same here...
print(smb.has_authenticated) #true if empty

Authentication (with extended security) successful! #username+password empty
vs.
Authentication (with extended security) failed. Please check username and password. #username+password correct

So maybe you like to open an issue or switch to impacket???

Maybe I can check it at the weekend. Stay tuned.

class MyButtonClass(ui.View):
    def __init__(self, x, y, height, width):
        self.x = x
        self.y = y
        self.height = height
        self.width = width

class SpecialButton(object):
    def __init__(self):
        self.view = ui.View()
        self.view.present('fullscreen')
        self.btn = MyButtonClass(100, 100, 100, 100)
        self.btn2 = MyButtonClass(200, 100, 100, 100)
        self.view.add_subview(self.btn)
        self.view.add_subview(self.btn2)

python classes

Try changing the draw method in this example.

import ui
import time
from random import choice

class myclass():
  def __init__(self):
    #self.v = ui.load_view('UIwithOtherName.pyui')
    self.v = ui.load_view()
    self.v.present('sheet')
    self.v.name = 'goapp'
    self.intro()
    self.key()

  def intro(self):
    self.v['textfield1'].text = "The Guitar Oracle is listening."
    time.sleep(2)
      
  def key(self):
    self.v['textfield1'].text = "Good bye."
          
myclass()

@cvp When you use smb.SMBConnection it is a synchronous connection and you can send only one command after another. So it shouldn't be necessary to flush the buffer, but there could be a small gap until the cache of the router is empty. However I'm not an expert, so I would still recommend to use an USB key with a LED.

@cvp I guess that your internet router has no (or a small) read/write buffer. Before you lose data I would recommend to use a USB key with a LED, to get sure that your router has enough time to write all data.