Update the Windows Registry to create or change the TcpMaxDataRetransmissions
The problem of PuTTY or other SSH connections timing out too quickly when network connectivity is briefly lost is Windows problem and not an internal PuTTY problem. You can tweak the Windows Registry settings to try and change or address this issue.
For Windows NT, 2000, XP – the registry key to create or change is:
It must be of type DWORD. See Microsoft Knowledge Base articles 120642 and 314053 for more information. Set the key’s value to something like 10. This will cause Windows to try harder to keep connections alive instead of abandoning them.