SMB (cifs) mounts disconnect then re-connect after 20 seconds (approximate)

Environment: Typo3 CMS 7.6.15 on a Red Hat Linux 7.3 (Maipo) server and Apache web service. I have SMB/cifs mounts to 30 different directories on a Windows 2016 server. The SMB version 2.0 is specified in each mount statement.
The directories and file contents are then displayed on Intranet web pages, configured with TYPO3’s Plug-in “File List - list of files” and mode = “files within a folder”.
When all the mount points broke on a Linux server reboot 2 weeks ago, we added vers=2.0 to all the mount statements in a connectWindows script and in /etc/fstab . This re-established the mount connections. But every two days or so, the mount connections break / dis-connect for 20 to 30 seconds, and then restore automatically.
The error on the web page is similar to: causal\FileList\Controller\FileController ERROR:
Folder “/test_dir/” does not exist

Hi Brian,
this is probably more a question about Samba and probably better answered at
TYPO3 indeed expects directories to be always available, at least when using the (default) LocalDriver.

Thank you. I will investigate it at