The hSE subnet cannot be accesses
I have seen this error while opening the FF Builder from control structure, from the system restored with maintenace back-up of some other system.
I hope this is the case with your system too.
I suggest you to check the following:
When the system is restored with back-up the following might be missing:
1. Open the configure window from start menu, Start --> Programs --> ABB Industrial IT 800xA --> Device Mgmt --> FOUNDATION Fieldbus --> Configure.
2. General Setting: Check Client/Server Network Inteface and HSE Subnet Interface IP Address(s).
3. Fieldbus Builder FF: Check Resource ID is not missing.
4. OPC Server FF: If the Resource ID is missing, specify the same in New resource ID and click on Add button.
5. Ensure that, FF Management aspect is also available apart from FFUpload aspect at HSE Subnet level under Control Structure.
6. Restart the server after above settings if any one missing.
It should work after the above steps. Let me know if you the problem still persist after configuration of above settings.