My Internet keeps being Limited

Hello,
I am using a Dell Inspiron 17 3721 Laptop. I keep losing my internet; when I look at the internet icon it has an asterisk and says limited. I have been disconnecting and then rebooting my gateway and cable by turning it off and disconnecting from the cable. You know, the whole route. Then it works fine for awhile usually about once a day I have to do this.
I have been having this problem for quite some time and originally thought it was because my linksys gateway was old (about 9 years). Then My cable company told me it was because they had upgraded to 3.0 and my equipment was 2.0. I have had the cable guy come out and install a really nice router/modem. and still the problem persists. I should mention that sometimes I will have full bars until I open my browser. then it will drop to 1 or 2 bars. My laptop is about 20 feet away from the modem on a straight line with nothing between them. I only get full bars if I am right on top of the modem.

I contacted Dell Support and they checked the laptop and found everything was fine. The drivers are up to date (automatically updated). They suggested that maybe a microwave, refrigerator or TV might cause the problem, but those things are not between the laptop and modem or even close. They then said I should get a wireless booster.

Can this be right? Shouldn't I be able to get a better connection than this without extra equipment?