We had the same issue Mia. Our ISP was useless though because they said they could see a good signal and connectivity from their end. And, when we took the router (went through three!) out of the loop, we could connect with no problems. ISP sent a tech out here twice and of course it worked beautifully for him!!! Then it would die within days so we kept replacing the router.
I found out indvertently that the ISP was onsite tweaking something on our complex (I live in a condo, not a house) and after weeks of back and forth, we got permission to install a small hub directly into the access panel in our unit. Our initial issue was that every room in this condo is pre-wired for cable/internet but they will only activate one port at a time (ISP rules, our cable/internet service is part of our homeowner's dues -we're held hostage). I raised ten kinds of heck until they approved the hub. Now I can plug in as many machines as I want.
Bottom line: be prepared to fight your ISP. They told us that they "don't troubleshoot hardware and since we could make one port work, they wouldn't help us". Your situation is probably a lot different since you are in a house. Can you do without a router?
I'd greatly prefer to have the router. If not, then the laptop will have to always be setup in the guest room, b/c that's where the internet cable is. There's all kinds of issues with the wiring of this house. *sigh*
Plus, once the bf is back for good, that's where his desktop computer & Xbox is set up and then I just use the wireless to connect my laptop to the internet. Plus, there's no tv in there, so it would just suck overall. LOL
I tried to plug directly into the modem Saturday night but and there's a connection, BUT it won't "acquire an address" so there's "limited to no connectivity." I unplugged everything for like 5 minutes and then just plugged in the modem before I tried to connect to it. Sigh. Then yesterday I just didn't want to mess with it. I'll see what I can get going tonight and if it's the same result then I'll call TWC tomorrow.