[BO2] can't find matches/online players on my Xbox 360

It always worked fine for me, but suddenly the number of online players doesn't appear. When I go to the game mode selection menu, the number of players in each mode doesn't appear; they're all at zero. And when I search for a match, it doesn't analyze or find any.

I tried connecting my Xbox to my phone's Wi-Fi hotspot, and then everything related to online players appeared, although I couldn't enter a match (although I understand that the latter is normal when using a hotspot).

What's going on? I can play all kinds of online games normally, including other CoDs such as Ghosts or WaW, but this only happens with BO2.

Does anyone know what's going on? Has this happened to anyone else? Is it a problem with my internet?