Ralph's comment does ring a bell, that I have seen that before, but can't remember when.
If it was installed a year ago it should be 4.2 then I guess, which is compatable with MBG 7.1, so all good there.
If you log in to the MBG server, go in to the MBG panel, and then status, file transfer. From there you can select the TNA tool to download.
Once installed, connect to the internet from outside of your network, and point the software to the public IP address of your MBG server.
I would think that all should show up fine, as it's usually UCA that gives hassles, but it's worth checking anyway.
The next places to look after that would be the event log, and the tug log, as they should give some hints as well.