When I log off the game and log back the next day, my progress is lost and restart when I started the last day, I got like 30 depot credits and the next day they were back at 8. Same thing for my rank, my class changes and the items I buy
Hmm, that is very weird and frustrating. And your game isn't crashing or freezing? It just loses progress on its own everyday?
I would suggest speaking to Official Activision Support via live chat whenever you get a chance, maybe they can help you figure out what's going on. In the meantime, I would suggest restarting your game console completely and restarting your router and checking the NAT type to make sure there's nothing wrong with your internet connection.