ssh_exchange_identification: Connection closed by remote host under Git bash
Solution 1:
I had this problem today and I realize that I was connected to 2 differente networks (LAN and WLAN), I solved it just disconnecting the cable from my Ethernet adapter. I suppose that the problem is caused because the ssh key is tied with the MAC address of my wireless adapter. I hope this helps you.
Solution 2:
I just ran into this today and it was because the server I was trying to connect to was overloaded with processing. So it may be possible that the server is low on memory or CPU starved.