I am paying for 200Mbps but often get only 10, which makes it impossible to stream video, even YouTube.

Is this with a WiFi connection ? If so, as a test, does a computer / device that is hardwired directly to the router / gateway device with an ethernet cable have the same problem ?

With this test, we are trying to isolate this down to being either a WiFi-only problem or a problem with the general connection to the Comcast system which would of course affect both. It's a good first step in troubleshooting before proceeding any further. 

Sounds like you have two things going on. Here are some tips for improving WiFi performance;

http://corporate.comcast.com/comcast-voices/10-ways-you-might-be-killing-your-home-wi-fi-signal 

https://forums.xfinity.com/conversations/internet/answered-how-to-improve-your-xfinity-wifi/602da486c5375f08cd804f16 

https://www.xfinity.com/support/articles/internet-connectivity-troubleshooting?linkId=180985598 

There are other options. Google for WiFi repeaters / range extenders, WiFi mesh systems / pods, powerline ethernet adapters.

https://www.cnet.com/how-to/your-router-isnt-as-fast-as-you-think-it-is-heres-why/ 

https://www.cnet.com/how-to/home-networking-explained-part-2-optimizing-your-wi-fi-network/ 

https://www.smallnetbuilder.com/wireless/wireless-features/wi-fi-ping-spikes-causes-and-fixes/ 

 And what do the modem's signal stats look like ? Try getting them here; http://192.168.100.1 or here http://10.0.0.1 

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.

What is the exact make and model number of the modem / gateway device ?

Make and model number?  XFSETUP-5FD5.  Do you need more numbers/letters?

As for signal stats -- the first one times out without loading.  The second will not accept any user name I give it.  I can't imagine what it is looking for.

The router is 16 feet from where I usually use my laptop.  Restarting the router sometimes helps and sometimes does not.  I sometimes restart it several times a day.

The fellow I take my computers to for fixing, says that the laptops work fine in his shop.

I am by no means a tech expert.  I appreciate your efforts, but I am getting grouchy over this. : -))

@

spvz29

@spvz29 replace coaxial cable that's all too it. let Technician know something wrong with the coaxial cable and they will use a signal meter to check to see what's wrong with it.

@spvz29 

Still there ? Signal stat values and model of modem ?

As a IT guy for 28 years you loose 35% of the speed through the hubs and equipment they use since it is all junk.  They advertise the max speed but no one will ever get that speed it is false advertising for xfinity 

Wonder how the original poster @spvz29 is making out........ ?

I have had a couple of my comments fail to post.  I will try yet again.

I have been to three computer repairmen and had an Xfinity tech investigate my problem with internet speed tests.  The last repairman changed the hard drive of the laptop and the network adapter, for free.  The Xfinity tech showed that the strength is over 200mbps on the wifi network and the line leading to the hardwired computer.  Both computers still test at well under 100mbps.  The laptop still has the problem of, at times, dropping to near zero, which means that the video freezes and audio stutters, then stops.  I guess that the problem cannot be solved.

My thanks to everyone who commented and made suggestions.