A.7.9 PuTTY's network connections time out too quickly when network connectivity is temporarily lost.

This is a Windows problem, not a PuTTY problem. The timeout value can't be set on per application or per session basis. To increase the TCP timeout globally, you need to tinker with the Registry.

On Windows 95, 98 or ME, the registry key you need to create or change is

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\
  MSTCP\MaxDataRetries

(it must be of type DWORD in Win95, or String in Win98/ME). (See MS Knowledge Base article 158474 for more information.)

On Windows NT, 2000, or XP, the registry key to create or change is

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\
  Parameters\TcpMaxDataRetransmissions

and it must be of type DWORD. (See MS 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.