After Doing a (cold) boot I have no internet connection.
But I actually can restore the connection with Window's Network Diagnostics:
According to the diagnostics the problem is
"No valid IP-Configuration"
and is solved by "resetting the LAN-Connection".
However, the problem persists and I have to run the diagnostics after every boot. Is there a way to fix this permanently?
EDIT: While trying some commands I found that 'ipconfig /renew' gives a time out error:
"DHCP-Server not found"