Getting disconnected for apparently no reason (Lordaeron)

Hello everyone! I have some issues playing on Lordaeron because every once in a while I get a DC for no reason. I thought it was for "inactivity" because it happened often while I was auto-running or on gryphons, but now it happens also while I'm in dungeon or while leveling and it's really annoying because it kicks me from every group and instance.
I had this problem on Deathwing too and I think it's related to my connection, with every "spike" of lag resulting in a disconnection... Is there a way to "prioritize" Warcraft in terms of bandwidth or something similar to prevent these spikes? I guess not, but this thing is really compromising my will of playing and I think this realm is too awesome to be real so that would be a shame.
Thanks for your time and patience, I'll wait for answers.

P.S. now I've been away from the game while writing this topic with my char in Stormwind, but he's still standing with no disconnection. A few minutes ago I disabled the wifi on my phone, could it be related? It's not a conflict of IP addresses because I set them static and they're different.

EDIT: I have Premium rank so it's not related to freeing online space for donors accounts.