TWC can run a ping on his modem and tell exactly what is going on remotely, had them for 10 years. Modem compatibility is a big issue with them. Buy your own modem, go to TWC and they have a compatibility list with modems that will handle your speed.
For wireless it isnt a big issue, the router needs to have the speed on both bands for optimum performance. As I said before I ran 4 computers, 3 diffrent Roku streamers and was getting 40 mbps down and 10 mbps up on a wireless setup and 30 Mbps plan had absolutely no problems. Sometimes with placement of the wireless router walls and power boxes tend to give it fits. Try diffrent placements if possible, if not get a range extender to fill in the voids.
