Possibly, setting the OBi Ethernet port to full duplex will help.
To force OBi to 100Mbit/Full duplex:
Pick up phone, press *** 0 option 27#, press 1, value=1#, press 1 to save, then hang up phone.
If done correctly, the link light on the modem for the OBi's port should change from amber to green.
Ask the cable company to upgrade the modem firmware to the latest version, if that is not currently installed.
If the above doesn't help, you might find a clue as to what has gone wrong by examining the modem's status pages (after connectivity lost and before rebooting).
The Status Configuration Page of the modem has a Reboot button, which may regain access without having to cycle power.