Nextcloud Client 2.6 lose temporay the connection

Hey, since the Client Version 2.6 my Client lose temporary the Connection.
After some seconds (sometime minutes) the connection is working again.
I thougt, that mybe the issue is gone, when i update NC from 16.05 to 17 but the connectiondislog is still there.
An old client like 2.5x is working fine.

I am hosting NC here:

Also someting strangeā€¦ When i do a security scan of my installation the systemcheck said, that i have installed NC 15.

Any ideas whats going on?

Greetz Hexo

Hey, am i the only one with this problem?