Ok, I was able to setup Visual SVN to use the SVN protocol. Then I relocated to the SVN protocol repo. and unreal was not working. Then I switched back to the http protocol and the unreal connection was working again.
So its the SVN protocol. In 4.14 the SVN protocol was working. In 4.15 http is still working but SVN not. I will try now to reconfigure our linux server to use SVN via Apache and http.