If you're using Private Network: Chances are when Collabspot is trying to access your Sugar, your Network may have restricted request coming from Collabspot. It is very important that your Network allows access to Collabspot's Server. Your IT or Admin must allow access to the following IP addresses:
Please open up HTTP (80) and HTTPS (443) ports for the 3 IP addresses:
Please take note that these are only for the backend instances that perform the calendar/contact synchronization. They are running on Google Compute Engine instances.
The page that the user uses to provide their Sugar credentials to setup the sync though, is running on Google App Engine. Google App Engine does not have static IP addresses that could be easily filtered.
The "Static IP Addresses and App Engine apps" section in the App Engine FAQ explains this and details a way to retrieve a list of current IP ranges used, but that new IP ranges could be introduced without prior notice.
Below is the current full list of IP ranges following the instructions from the FAQ:
# nslookup -q=TXT _cloud-netblocks1.googleusercontent.com 18.104.22.168
# nslookup -q=TXT _cloud-netblocks2.googleusercontent.com 22.214.171.124
# nslookup -q=TXT _cloud-netblocks3.googleusercontent.com 126.96.36.199
# nslookup -q=TXT _cloud-netblocks4.googleusercontent.com 188.8.131.52
# nslookup -q=TXT _cloud-netblocks5.googleusercontent.com 184.108.40.206