Rebooting BBB w/ USB connected trashes host connection to internet.

Rebooting BBB w/ USB connected trashes host connection to internet.

Network configuration:

Cable modem (192.168.100.1) to internet connected to:

Router (192.168.1.1) connected to:

Ubuntu host (static 192.168.1.10)

and

BBB (static 192.168.1.15)

BBB (192.168.7.2) is also connected to host (192.168.7.1) via USB and Putty.

Ubuntu uname -a

Linux ubuntu1 3.16.0-44-generic #59~14.04.1-Ubuntu SMP …

BBB uname -a

Linux beaglebone 3.8.13-bone79 #1 SMP …

On initial startup, everything seems to work fine. I have full terminal access from my host to the BBB via Putty. I can ping both my router and my cable modem from both the BBB terminal and a terminal window in my host. I can access the internet with my host browser.

When I restart or reboot the BBB with the USB cable connected to the host, I can still connect to my BBB with Putty on the host. I can also ping both my router and modem from the BBB.

HOWEVER, I cannot ping either the router or the modem from my host terminal.

BUT, if I reboot the BBB again, my host can now ping the router, but not the cable modem.

AND the BBB can still ping both the router and the modem.

This condition is maintained no matter how I reset, power on/off, or just plain disconnect the BBB from everything. Until I reboot my host computer, it cannot ping the modem or browse to the internet.

With the BBB powered and connected to the router, but not the host USB, it has no effect on how my host connects to the modem and internet.

Question: Why does the BBB USB connection to my host computer cause my host computer to not connect to the cable modem even though my host connects to the router? And why does it only happen after I reset the BBB when it is connected to my host via USB?

More importantly, how might one fix it, please?

Thank you for your time and consideration.