Failed to connect to github

Hello,
yesterday i installed a fresh Linux and Linuxcnc. Today i received a handwheel for my mill. During the installation prozess i have to use the terminal window with the command:git clone github.com/LinuxCNC/linuxcnc linuxcnc-dev I get this error:
Cloning into 'linuxcnc-dev'...
fatal: unable to access ' github.com/LinuxCNC/linuxcnc/ ': Failed to connect to github.com port 443 after 3 ms: Couldn't connect to server

 I can´t reach many https sites. Any ideas? I don´t have a proxy and (probably) no firewall

Thanks

Works here.
Can you access google or youtube or www.linuxcnc.org ?

www.linuxcnc.org don´t work
Reddit    don´t work
Youtube work
Google  work

My Windows Laptop (WLAN) and my Smartphone (WLAN) have no problems

It works now...
I have two network adapter. One intern and one USB. My Internet was connected to the USB adapter. This doesn´t work. I switched to the intern adapter and now itś fine...