Modem and Wifi speeds

I currently have a DOCSIS 2 modem for comcast. If I upgrade to a DOCSIS 3 modem can I expect improved speed via my WiFi network. Currently, my TV is in one bar territory, and when watching streaming video it frequently has to stop to buffer.

Not much info to go on, so I’ll have to extrapolate and deduce.
Changing your modem won’t get you better speed from the provider - you need to get (and pay for) faster service from the provider too.
Changing your modem doesn’t have anything to do with the speed of the WiFi connection to the TV. Unless the modem is also your router / Wireless Access Point (a quick google of ‘DOCSIS 3’ show’s it’s a technology, not a brand so no way to know).
“one bar” is (I believe) WiFi signal strength, which isn’t absolutely tied to speed of the WiFi. Can you move the WAP closer to the TV?
You need to determine if your issue is internet service speed or WiFi connection speed:
Connect a laptop or computer directly to you modem and do an internet speed test.
Then connect to the WiFi and do the same speed test.

I am sure the problem is WiFi speed. I was hoping that a faster modem would present the router with more information per second, and so it would be able to send more information per second. If I had thought on it a minute, I would have realized that since neither is currently working at capacity this would not help.