KB1781: Connection forcibly closed by remote host
https://www.veeam.com/kb178105.07.2013 · Typically this issue is related to packet loss somewhere on the network between the two servers. There are some utilities to test the line, it is advisable to involve the ISP or networking team. Some common tools typically recommended for testing are Iperf as it can give quite a bit of information about the network connection and Wireshark.