Does the connection sort of overload? and shutdown?
I'm not sure what you mean? I don't think it ever works correctly in the first place. I've gotten the NAT error from the get-go. Apparently the ports are not being forwarded correctly, but I can't figure out why.
I'll try opening up some more ports around the specified port per EricB's comment.
By the way, my download speed varies from 30k to 5k, mostly staying on the low end of this range.