Software update can't connect to the Apple Software Update server

So apparently it has enough internet to download the update manifest and suggest installing Catalina or Mojave supplemental update and Safari 13.0.2, but not enough internet to download the updates themselves?

My internet connection is fine, nothing blocks it, i tried to cleanup the catalogue (sudo softwareupdate --clear-catalog) as suggested somewhere, but so far i'm unable to install any updates from the SU (AppStore works fine though).

Any suggestions?