Guest Frequently Loses Connection to Host

[ags799]

Hello,

My host OS is Windows 7. My guest OS is Lubuntu 14.04. I have an SSH server running on the guest. I am using port forwarding so that I can SSH from the host to the guest via putty.

I can successfully connect, but after 3 minutes or so of normal activity, putty freezes and gives the error "Server unexpectedly closed network connection." In order to further understand this problem, I ran the Virtualbox GUI at the same time I ran putty. When putty quit, the Virtualbox GUI displayed its own error message about a disconnected ethernet cable. That message may be coming from the Lubuntu GUI, I am not sure. It's displayed as a gray box in the top right corner.

The guest's only connected network adapter is a NAT.

Any ideas why the ethernet connection is getting disconnected so often?

Thanks in advance.

[mpack]

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