Display error in Fusion with wavy pattern

We are rendering a huge Fusion tree, with several multipass EXR source files. Sometimes (not all time) we experience a glitchy lined (wavy) pattern on the rendered result images. See the screenshot attached.

It's only happening when we are using a network fileserver. We tested it on several dual Xeon workstations, and NVidia cards (for example Tesla) (I can write you the exact configs). If we render locally (source files are on c: SSD), it's going without error. Although, the speed of the fileserver is fast, there are no network issues.

In a previous post, someone else also had this error without any solution/reply: viewtopic.php?t=47727

Can anyone help, how to solve this?

That's the license error pattern. It means no license was found. Why they break renders rather than just stop with a useful error, I have no idea.

In a network setup, I guess check the render node has continuous access to the licensed fusion studio instance and check that machine has a working license eg no dodgy USB port etc (if using a dongle) . On windows you can check the Windows Event Log to double check for USB port errors.

That's the license error pattern. It means no license was found. Why they break renders rather than just stop with a useful error, I have no idea.

In a network setup, I guess check the render node has continuous access to the licensed fusion studio instance and check that machine has a working license eg no dodgy USB port etc (if using a dongle) . On windows you can check the Windows Event Log to double check for USB port errors.

Thanks for the answer! We are using Fusion remote connection to AWS (Amazone cloud) via Terradici client, and the USB dongle is forwarded there, so that can cause this error, probably it's losing the dongle connection during the renders for shot time...
Blackmagic couldn't swap our dongles to serial numbers, which were a better solution working with cloud rendering, so we would need no USBs