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As an alternative it can also be done programatically following this link

 $AllowInternet = False 

Or to the frontend

You can use:

CurrentValue[$FrontEnd, "AllowDownloads"]=False;

to disable the "Allow the Wolfram System to access the internet" preference.

Update

Wolfram support presented yet another solution

Configure your machine to disable internet access to the Wolfram domains:

https://support.wolfram.com/kb/12409

(though this link does not work as of today!)

As an alternative it can also be done programatically following this link

 $AllowInternet = False 

Or to the frontend

You can use:

CurrentValue[$FrontEnd, "AllowDownloads"]=False;

to disable the "Allow the Wolfram System to access the internet" preference.

Update

Wolfram support presented yet another solution

Configure your machine to disable internet access to the Wolfram domains.

As an alternative it can also be done programatically following this link

 $AllowInternet = False 

Or to the frontend

You can use:

CurrentValue[$FrontEnd, "AllowDownloads"]=False;

to disable the "Allow the Wolfram System to access the internet" preference.

As an alternative it can also be done programatically following this link

 $AllowInternet = False 

Or to the frontend

You can use:

CurrentValue[$FrontEnd, "AllowDownloads"]=False;

to disable the "Allow the Wolfram System to access the internet" preference.

Update

Wolfram support presented yet another solution

Configure your machine to disable internet access to the Wolfram domains:

https://support.wolfram.com/kb/12409

(though this link does not work as of today!)

As an alternative it can also be done programatically following this link

 $AllowInternet = False 

Or to the frontend

You can use:

CurrentValue[$FrontEnd, "AllowDownloads"]=False;

As an alternative it can also be done programatically following this link

 $AllowInternet = False 

Or to the frontend

You can use:

CurrentValue[$FrontEnd, "AllowDownloads"]=False;

to disable the "Allow the Wolfram System to access the internet" preference.