Getting XML error when trying to install package on VS 2017

[GiganteX]

I'm using VS 2017 and docker version of Klondike 2.1.1 :

"Failed to retrieve information about 'DevExpress.Xpo' from remote source 'https://nuget.nebol.se/FindPackagesById()?id='DevExpress.Xpo'&semVerLevel=2.0.0'.
The content at 'https://nuget.nebol.se/FindPackagesById()?id='DevExpress.Xpo'&semVerLevel=2.0.0' is not valid XML.
For security reasons DTD is prohibited in this XML document. To enable DTD processing set the DtdProcessing property on XmlReaderSettings to Parse and pass the settings into XmlReader.Create method."

In this case the package doesn't even exist on my server, it's in another repository. But if I try to get something from my own server I get the same problem.

What's could be going on here?

[MaxSierra16]

Getting a similar error updating package Humanizer.