Connection to mounted network drives failing after some use

I have a user who uses a Macbook Air that is on MacOS Mojave 10.14.3. He has an issue where he connects to the network drives on our file server and after some time encounters this exact issue:

I wanted to ask if anyone has any new information on it since his OS version is definitely a few steps up from what are described as the problematic versions? Or if anyone has found a cause for it that can be mitigated? The only third party softwares he has are Office 2016 for Mac, Webex client with Outlook add-in, and SEP 14. Anyone have any ideas? Thanks!
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