That’s very strange the shutdown would affect an already funded contract. Perhaps you are paid by contingency? Are you a consultant? My understanding is consultants are paid with general operating funds. They may want to preserve those in this case. Or perhaps they cannot provide facility support?
Best of luck to you. If I were you I’d start working another job immediately as the old one will eventually return and there’d be a choice.
Once again: You cannot bill for hours you do not work, and I am forbidden by law from accessing any Federal web- or physical-asset during a shutdown.