I had a similar problem because I was using an apt proxy to download the packages. Because of this, the ttf-mscorefonts-installer package wanted to use the apt proxy to download the fonts, but the proxy is Debian-packages-specific, so it couldn't handle the ms fonts downloads, making the installation fail, even when a good working internet connection was available.
I did a:
dpkg-reconfigure -plow --force ttf-mscorefonts-installer
to remove the proxy from the settings and the package was installed successfully.
I had a similar problem because I was using an apt proxy to download the packages. Because of this, the ttf-mscorefonts -installer package wanted to use the apt proxy to download the fonts, but the proxy is Debian- packages- specific, so it couldn't handle the ms fonts downloads, making the installation fail, even when a good working internet connection was available.
I did a: -installer
dpkg-reconfigure -plow --force ttf-mscorefonts
to remove the proxy from the settings and the package was installed successfully.