selenium.common.exceptions.WebDriverException: Message: connection refused

After Struggling a while I decided to post my "dead end" running InstaPy on raspberryPi 3b+. I can't go further. I already Google the heck out of this error with no success :(

When I run a quickstart.py, firefox window opens after couple of seconds and shows nothing. After 20-30 sec closes and I get this error message...

Geckodriver 0.23.0 ( 2018-10-04)
Mozilla Firefox 52.9.0
python3-selenium (2.53.2+dfsg1-1)
xvfb is already the newest version (2:1.19.2-1+rpt1+deb9u2)

```
InstaPy Version: 0.6.6
._. ._. ._. ._. ._. ._. ._. ._.
Workspace in use: "/home/pi/InstaPy"
Traceback (most recent call last):
File "quickstart.py", line 70, in
headless_browser=True)
File "/home/pi/.local/lib/python3.5/site-packages/instapy/instapy.py", line 319, in __init__
self.logger,
File "/home/pi/.local/lib/python3.5/site-packages/instapy/browser.py", line 114, in set_selenium_local_session
options=firefox_options,
File "/home/pi/.local/lib/python3.5/site-packages/selenium/webdriver/firefox/webdriver.py", line 174, in __init__
keep_alive=True)
File "/home/pi/.local/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py", line 157, in __init__
self.start_session(capabilities, browser_profile)
File "/home/pi/.local/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py", line 252, in start_session
response = self.execute(Command.NEW_SESSION, parameters)
File "/home/pi/.local/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
self.error_handler.check_response(response)
File "/home/pi/.local/lib/python3.5/site-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: connection refused
```

まず、報告されている InstaPy、Python、Selenium、Firefox、Geckodriver、Xvfb のバージョンを使って quickstart.py で失敗を再現します。instapy/instapy.py と instapy/browser.py をたどって traceback を読み、その後、ブラウザーセッションのセットアップを Raspberry Pi 環境と比較します。確認済みの原因を特定し、動作する起動手順を文書化または検証できれば完了です。

索引モデルが issue の本文から書いたものです。