What specifically loses Internet service? A modem losing service is 1 thing because it's hardwired to the network in your neighborhood.
A device losing service is something else because it's wired or wireless to your network (router). So, you have 2 networks to consider: neighborhood or router.
Do all devices lose service or only the primary PC?
Why did you suspect the modem? Was the modem indicating a problem?
Granted, the cabling outside your condo may have been getting faulty and eventually needed to be replaced; however, this may not have been the original problem. It may have been soon enough but it wouldn't have affected wireless. I would have troubleshot the router.
If you're renting a combo device, however, you may have indirectly troubleshot the router by replacing...but it apparently didn't solve the problem. What's the make/model of your router?
