reply to CYYZ
Glad you got your issue narrowed down - I guess your issue is different than mine. However, "maintenance" has a broader implication than what I may have suggested above. Your problem has been ongoing for two months, so likely Rogers did do something two months ago which affected DHCP provisioning for your modem - this is still maintenance, and it's still Rogers' fault, and I agree, it shouldn't have been up to you to figure that out. The fact that your father's modem worked is likely because Rogers ties IP addresses to MAC addresses (I noticed this in the last couple of months dealing with TSI on my issue), and whatever maintenance Rogers did didn't affect his provisioning. TSI and Rogers should have been able to isolate and resolve this long ago, if indeed that's what it is. Network troubleshooting should never be on the onus of the customer - it's an added "bonus" for TSI customers.
Given your new modem and updated firmware, I agree that it's very unlikely to be a modem problem, unless the replacement they sent you was also defective.