Got Disconnected Twice From T17, Lost 2 Maps and Gold

I've been disconnected from server during map Citadel t17, when I logged back in, I noticed in my hideout that all of my portals were gone. After that I bought another map to run, and it happened again in the exact same order as before.
Why my portals dissappear in hideout when I log back in?
What can i do to prevent this from happening?