If no other (filemaker) user is having an issue on the same network, then all signs point to the computer itself that user is on.
Setting idle timeout will not change anything because the computer is still communicating to FMS to tell it "I've been idle for ___ minutes".
The communication disruption message occurs when network communication between the client and host fails completely. For the user side, they get a dialog box stating as such. On the server side, the server notes that it lost communication with the client with the message above.
Without knowing the specifics of your environment, I would check to make sure their system configuration is compatible with FM13:
If the IT department is comfortable performing a backup and reformat, that might be your fastest option rather than trying to troubleshoot this further.
Also, the IT department should have a network monitor or packet sniffer setup to measure their network traffic. If you guys are getting DDos'ed on a regular basis by an infected local machine, that could be flooding your network, usually that's not random though, but all the time.
Thanks, its all users being effected. Their Setup is all compliant. I will suggest the Packet Sniffer.
You might also want to see if anything is conflicting with the filemaker ports. FMS13 uses port 80, so that could be a conflict
Just to close this one off, It turned out to be a users personal phone, the wi-fi connection was hijacking the Filemaker Server's IP address!!
That's an odd one, not sure what your DHCP settings are on that network, but device connections that try to use a local IP that is already on a DCHP lease should be rejected if your DHCP is set up correctly. Glad you got it sorted out.