Defender takes to long for Matlab to execute its task

Problem: One of the problems are the MatLap servers
The servers behave a bit strangely in Maitanance Mode, the storage of Excel files seems to work but not again after a reboot.
They are Windows 2016 servers with Matlab version 2019a and Office version 2016 (16.0.5443.1001 32 bit)
The error message is :

This error occurs in connection with Matlap but also with pure Excel copy processes via VBA.
What has been tried :
1. reinstalled Symantec without uninstalling Derfender.
Defender was still active (it does not go into the background)
2. uninstalled Defender
without success Error still occurs .
3. offboarding performed .
Excel can write to \\fsp again.
Writing to C: is possible at any time even with servers that are onboarding.

Exclusions have been set but do nothing
I do not see any hints neither in the Defender Portal nor locally
Deactivating Real Time Protection or all features in general does nothing

Any Ideas to fix this Issue?