I am a ziggo customer with an engineering background and I have confirmed that Ziggo is slowing down my connection when connected to a VPN which I need for multiple reasons including work.
I am using Tunnelblick with a OpenVPN UDP connection and there is no bandwidth issues through the VPN gateway. When I am not connected to the VPN, I get full speeds. When I am connected to the VPN, I get a maximum of 25 Mbps.
How does one resolve this? I see many other people complaining of the same problem. The situation does not change wether the VPN gateway is my work's VPN server or my own located in Switzerland who also confirms that they do not shape any traffic or have any bandwidth issues.