Realistically there isn't enough information being provided to be able to give a fix. For some reason the server is refusing to let you connect. This is different from a K-line or G-line, which would let you connect, then disconnect you.
I suspect, but this is not the only possibilities, that the server was too full or had too many requests in a short period of time, thus it had to refuse the connection until the resources to handle another connection were available.
While I've seen this on almost, if not, every network that I've connected to, at one time or another, the bigger the network, the more servers it will have, making this situation less likely.