BTW, if you use the computers with a wired connection, do you get the same problem? While I realize this would likely not be a long term solution if it does help, it would at least help try diagnose the problem.
FWIW, I cannot find any specs on the Netgear 7550. The wireless setup video on this Frontier page seems to imply that it at least has 802.11n due to one of the setup pages it shows in the video:
If 802.11n is what it has, then it is possible that it is an implementation of 802.11n while the standard was still a draft. If so, then it could very well be what I was originally thinking.
Without you answering most of the questions that Trikein and I asked, it is tough to try to diagnose anything. At this point, I am going to assume you did not change any of the default settings, which according to the Frontier website above seems to suggest that the setting are set to broadcast the SSID, MAC filtering is off, and they tell you to use "WPA Any" for encryption.
Without further information, the possibilities to me seem to be either:
1) The WiFI chipsets in the computers do not like the chipset in the modem/router along the lines of what I was thinking. This is related to the questions that I asked. If it is this, the way to solve it would be to get a third-party router that you place after/connect to the Netgear modem/router. Then use the third-party router for your WiFi and wired connections.
2) You are getting a weak signal from the router as Trikein suggested. If this is the case, the first thing to do is try to see if you can position the modem/router to provide a better signal (place it up higher with as few obstructions between the computers and modem/router as possible and try to locate it as close to the middle of the home as possible) and try a different WiFi channel. The more intensive options are trying to boost the signal with a repeater or purchasing a third-party router.
3) There is a problem with the modem/router. The fact that you seem to have no issue with your phone makes this less likely, it is still a possibility. If this is the problem, then getting a new modem/router from Frontier would solve it.
Have you tried calling Frontier? Presumably, you are renting the modem/router from them. If so, then they should support it.
In general, I don't like routers that ISP provide. Usually they are pretty crappy with weak WiFi. For my Internet through Comcast, I don't use the WiFi built into the modem/router provided by Comcast. I have a third-party router that has WAY better WiFi.