I've been battling with it too. Last I heard, each user has a bandwidth limit to prevent spamming. Usually, this limit is tied to your SP and gradually reduces each time you post, comment, upvote or resteem. So the higher your SP, the more bandwidth you have. It usually refills itself in about 6 hours (in my own case).

I actually experienced it about 8 hours ago and now I'm back

Blessings