Python requests [Errno 111] Connection refused when running on server, but not on local PC

Question

I have a web scraper script which runs fine on my (Windows) PC, but I'm trying to get it to run from a (Linux) web server. I have a number of other scripts which run fine on the server (connecting to different websites than this one), but when I run this script, I get a [Errno 111] Connection refused error.

Here is a minimal version of the script to demonstrate the problem:

import time
import requests
import urllib.request
from bs4 import BeautifulSoup

s = requests.Session()

target = "http://taxsearch.co.grayson.tx.us:8443/"
headers = {"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8",
           "Accept-Encoding": "gzip, deflate",
           "Accept-Language": "en",
           "Cache-Control": "no-cache",
           "Connection": "keep-alive",
           "Host": "taxsearch.co.grayson.tx.us:8443",
           "Pragma": "no-cache",
           "Upgrade-Insecure-Requests": "1",
           "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36"
}


time.sleep(1)
response = s.get(target, headers=headers)

if response.status_code == requests.codes.ok:
    results = BeautifulSoup(response.text, 'html.parser')

    # Do something with output
else:
    response.raise_for_status()

This runs fine on my PC, but when running on the server, I get the following error:

Traceback (most recent call last):
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/connection.py", line 159, in _new_conn
    (self._dns_host, self.port), self.timeout, **extra_kw)
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/util/connection.py", line 80, in create_connection
    raise err
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/util/connection.py", line 70, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/connectionpool.py", line 600, in urlopen
    chunked=chunked)
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/connectionpool.py", line 354, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/opt/alt/python36/lib64/python3.6/http/client.py", line 1239, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/opt/alt/python36/lib64/python3.6/http/client.py", line 1285, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/opt/alt/python36/lib64/python3.6/http/client.py", line 1234, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/opt/alt/python36/lib64/python3.6/http/client.py", line 1026, in _send_output
    self.send(msg)
  File "/opt/alt/python36/lib64/python3.6/http/client.py", line 964, in send
    self.connect()
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/connection.py", line 181, in connect
    conn = self._new_conn()
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/connection.py", line 168, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x2af700598c18>: Failed to establish a new connection: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/requests/adapters.py", line 449, in send
    timeout=timeout
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/connectionpool.py", line 638, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/urllib3/util/retry.py", line 398, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='taxsearch.co.grayson.tx.us', port=8443): Max retries exceeded with url: / (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x2af700598c18>: Failed to establish a new connection: [Errno 111] Connection refused',))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "../python/grayson-2year.py", line 22, in <module>
    response = s.get(target, headers=headers)
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/requests/sessions.py", line 546, in get
    return self.request('GET', url, **kwargs)
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/home/jken/virtualenv/web-scraper/3.6/lib/python3.6/site-packages/requests/adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='taxsearch.co.grayson.tx.us', port=8443): Max retries exceeded with url: / (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x2af700598c18>: Failed to establish a new connection: [Errno 111] Connection refused',))

My guess would be that the issue here is down to some firewall issue on the webserver or something, but I'm really not sure. Is there something I'm missing?