Upload Problem still exist...

Hi all.
We changed our firewall system from Fortinet to Lancom. With Fortinet i had no upload problems, but with Lancom i cant´upload any files. I see always the error message at the top of the page which says "Something went wrong with the upload of...."
But it should work... My Admin showed me the grabcad entry in the whitelist of the firewall... Is there something special about it wo do not know ?
Has anyone an idea ?
Greets,
thorfynn aka Michael