Do you recommend calling Time Warner before trying a reset or can I just try the reset first?
I am still a little confused. If bridge mode allows only one computer to work at a time, why does my sisters laptop currently work even though the desktop is also plugged in? Why does hers work and not mine? Why does mine not work when I plug it in by itself with all the other computers offline/ unplugged?
Assuming they provide free phone help, you may as well just reset it. If doing so knocks you offline, they will help you fix it.
I would expect that they would only assign one IP address per customer unless you paid for more, but here's a post that might reflect your experience:
http://forums.timewarnercable.com/t5/Home-Networking/Multiple-Public-IP-Addresses-on-Arris-TG1672G-in-Bridge-Mode/td-p/73534In any case, whether the maximum for you is one or two IP addresses, those addresses are assigned to the specific MAC addresses of the first one or two devices that you connect after you turn on the cable modem. If you wish to connect an additional device, Time Warner will not assign an additional IP address. In all likelihood, you can get the additional device to work by disconnecting the first (or the second) device that does work and spoofing its MAC address on the additional device. Alternatively, you could turn off the cable modem, unplug the first device(s) that had worked and then plug in only the additional device that was not working and turn the cable modem back on.
However, you can easily get around the one (or two) device at a time restriction by either using the modem in router mode or by plugging in another router of your own if it's in bridge mode.
Here's another option that could work if your computer that does work is equipped with wireless in addition to its wired connection: you could tell Windows to share the internet connection that it has from the Ethernet wire with other computers that will connect to it wirelessly. I don't advise this in your case; it's much easier to just use your cable modem in router mode.