'OPCServer FF Status' in FF Builder goes 'No Connection' frequently
As you have neglected to give any real details on your system and/or architecure it is a little hard to resolve your issue. However if I assume a few things such as: your're using a recent version of 800xA and you are using the ABB LD800F HSE Gateways.
A lot of problems come from the fact that few have the FF HSE network separate from the Control Network which is a must. Check your Network connectivity and Network logs to ensure you are not getting some sort of conflict. Ensure the switches on your FF network are up to the task, as the FF network has many broadcasts (eg status) to run the FF data. If the service drops off on a rgeul;ar basis what is the timing? Does this correspond to any other events in the system (especially true if you do not have a separate FF network)?
The event logs are part of Windoes events and there are also some details within the HSE gateways.