PlexConnect issue

I have PMS and PlexConnect installed on my Synology. I see the following error in my PlexConnect.log:

19:50:35 PlexAPI: No Response from Plex Media Server
19:50:35 PlexAPI: No Response from Plex Media Server
19:50:35 PlexAPI: We failed to reach a server. Reason: timed out
19:50:35 PlexAPI: We failed to reach a server. Reason: timed out
19:50:35 PlexAPI: Traceback:
Traceback (most recent call last):
  File "/volume1/@appstore/plexconnect/share/PlexConnect/PlexAPI.py", line 426, in getXMLFromPMS
    response = urllib2.urlopen(request, timeout=20)
  File "/usr/lib/python2.7/urllib2.py", line 154, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib/python2.7/urllib2.py", line 429, in open
    response = self._open(req, data)
  File "/usr/lib/python2.7/urllib2.py", line 447, in _open
    '_open', req)
  File "/usr/lib/python2.7/urllib2.py", line 407, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.7/urllib2.py", line 1241, in https_open
    context=self._context)
  File "/usr/lib/python2.7/urllib2.py", line 1198, in do_open
    raise URLError(err)
URLError: <urlopen error timed out>

Anyone know what the cause of that is?
Settings.cfg:

[PlexConnect]
enable_plexgdm = True
ip_pms = 0.0.0.0
port_pms = 32400
enable_dnsserver = True
port_dnsserver = 53
ip_dnsmaster = 8.8.8.8 #also tried 10.0.5.1
prevent_atv_update = True
enable_plexconnect_autodetect = True
ip_plexconnect = 0.0.0.0
hosttointercept = trailers.apple.com
port_webserver = 81
enable_webserver_ssl = True
port_ssl = 444
certfile = /usr/local/plexconnect/etc/certificates/trailers.pem
allow_gzip_atv = False
allow_gzip_pmslocal = False
allow_gzip_pmsremote = True
loglevel = Normal
logpath = /usr/local/plexconnect/var

I added the cert via browsing to trailers.apple.com/trailers.cer. The server is using UPnP in case that makes a difference, but should be findable at 0.0.0.0:32400 so i'm not sure what else to try.