Not sure if this is the same issue you have but this is what I did.
Because my ISP is not Vodafone and I didn't have a Vodafone modem box I couldn't get it to connect, apparently there's some settings configured on their gear presumably so you just use Vodafone.
Anyway I got around it, there's just a few things I had to do.
1. I had to get a static IP from my ISP (which was a one off $45 charge). This is because when router/modem reboots normally your IP changes. Once I had a static IP, I Googled whats my IP and it told me my public IP address.
2. Next I had to configure the 'NAT' settings on my router/modem (mine is under the advanced setup). I added 5 virtual server entries for ports 8, 50, 123, 500 and 4500 all with protocol TCP/UDP and using my public IP address as the server IP address.
Once both these were setup the service worked.
Note, if you have anything else that connects to your modem/router i would disconnect it while the Sure Signal connects first. I have a second router that connects to my modem/router (to extend my WAN) and if it is connected while the Sure Signal is connected sometimes (not always) the Sure Signal box won't connect.
I had ordered a Vodafone connection so I could get one of their modems, but in the meantime, I reset my old Spark modem to factory default and that got the Sure signal to connect and I had full bars everywhere in the house.
Yesterday I was connected with Vodafone and got the new modem at it all worked straight away, so so far so good