I've had an RUT850 setup in my car for a while now and it's been working flawlessly.
I only just got around to setting up GPS and noticed SMS isn't supported on my mobile broadband plan so setup RMS.
Google and the forums helped me get GPS monitoring working but I've noticed that RMS doesn't automatically connect, it seems I have to manually hit connect from the router web interface otherwise it'll just sit there "Connecting".
Seems to connect straight away though so not sure why it's not able to do it automatically.
EDIT: So I jumped the gun on this one. Found the IP (18.104.22.168) so entered that instead of the hostname. Rebooted and, by the time I navigated to System > Administration > RMS, it was already connected. Consider this resolved!