Cause Connection Abort. Network error software causes Connection abort
Here’s how to resolve a puTTY connection outage:
1. Setting on the Linux server:
vi /etc/ssh/sshd_config
Find TCPKeepAlive Yes and remove the previous #
Find the ClientAliveInterval parameter and remove the previous #
ClientAliveInterval 60 Changes the following 0 to 60
ClientAliveInterval specifies how long it takes the server to request a message from the client. The default is 0 and no message is sent. ClientAliveInterval 60 means once a minute and then the client responds, which keeps the connection long. The oddity here is that instead of the client initiating the request to stay connected (FTerm, CTerm, etc.), the server is required to initiate the request first.
In addition, for ClientAliveCountMax, the default value is 3. ClientAliveCountMax means that when the server makes a request and the client does not respond to it a certain number of times, the client automatically disconnects. Under normal circumstances, the client will not fail to respond.
2. Putty client Settings:
In the Connection, there are Seconds between Keepaliaves, in which an empty packet is sent to the server to keep the Connection alive. In case the logged in host does not receive the data for a long time, it will automatically disconnect the SSH connection

In the figure above, the default input 0 is to disable keeping a connection, in this case I’m used to setting 60. Both check boxes remain selected by default.
From: https://blog.csdn.net/xiaobaoroy/article/details/51556320