I have had this similar query at one of my schools. They are now using Hosted Sims and the staff use Sims Learning Gateway to login and take the registers. Quite often I will get reports that the registers haven't saved, or that the teacher did save but it didn't get through when the Attendance Officer was looking. Quite frustrating and as Capita don't monitor connections they say it is down to your ISP. Quite often we will get 'reconnecting' when using the hosted session. It seems that there maybe services that 'stop running' but trying to get something from Capita is frustrating sometimes.
My next xtep is to ask the ISP (LA) if they can monitor the traffic.