CallStranger: urllib.error.HTTPError: HTTP Error 404: Not Found

Sometimes it finds more hosts, but mostly it just fails with the below stacktrace.

Ubuntu 18.04 w/ Python3 VENV, Python v3.6.9

Traceback (most recent call last):
  File "CallStranger.py", line 113, in <module>
    devices = upnp.discover()
  File "/opt/callstranger/upnpy/upnp/UPnP.py", line 33, in discover
    for device in self.ssdp.m_search(discover_delay=delay, st='upnp:rootdevice', **headers):
  File "/opt/callstranger/upnpy/ssdp/SSDPRequest.py", line 49, in m_search
    devices = self._send_request(self._get_raw_request())
  File "/opt/callstranger/upnpy/ssdp/SSDPRequest.py", line 100, in _send_request
    device = SSDPDevice(addr, response.decode())
  File "/opt/callstranger/upnpy/ssdp/SSDPDevice.py", line 82, in __init__
    self._get_description_request(utils.parse_http_header(response, 'Location'))
  File "/opt/callstranger/upnpy/ssdp/SSDPDevice.py", line 115, in _get_description_request
    device_description = utils.make_http_request(url).read()
  File "/opt/callstranger/upnpy/utils.py", line 80, in make_http_request
    return urllib.request.urlopen(request)
  File "/usr/lib/python3.6/urllib/request.py", line 223, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib/python3.6/urllib/request.py", line 532, in open
    response = meth(req, response)
  File "/usr/lib/python3.6/urllib/request.py", line 642, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib/python3.6/urllib/request.py", line 570, in error
    return self._call_chain(*args)
  File "/usr/lib/python3.6/urllib/request.py", line 504, in _call_chain
    result = func(*args)
  File "/usr/lib/python3.6/urllib/request.py", line 650, in http_error_default
    raise HTTPError(req.full_url, code, msg, hdrs, fp)
urllib.error.HTTPError: HTTP Error 404: Not Found