Just Upgraded Service and my Internet went from 300mbps to 600mbps, but I see no change on this end

Try calling 1-800-comcast and ask a rep to completely remove the modem from your account and to "re-provision" it from scratch. Also ask them to confirm that the provisioning and account data in their database is correct and complete and that the correct configuration / bootfile for your subscribed to speed tier is being pushed to the modem. Good luck !

It has been about 3 hours since the upgrade.  I powercycled the gateway about an hour and a half  ago. 

Have you tried power-cycling the gateway since you upgraded ? How long has it been ?

Thanks for the tips.  I called ,but did not get the sharpest agent.  She setup for a dispatch, but said she would try to have higher tier support look at.  Figure, I may wait a few hours and try to call again and see if I can get someone with more knowledge.  Not convinced that she pulled modem off and re-added. 

Today, had tech come out.  There is a problem on the line that they need to fix.  However, testing to my ethernet cable, seeing the 600mbps.  However, on desktop computer I can only get 350mbps.  Removed network adapter and re-installed.  No change.  What other items would you check that could be the culprit, since it is something in the pc.  Running Win 10 currently.  

Thanks,

Rob

Here is screenshot of latest speed test

Just got latest driver from Realtek for Windows 10 and upgraded.  Still no change.  I can get about 375mbps at most.  All screenshots and tech confirmed I am provisioned for 600mbps.  When he ran test on line got 700mbps from ethernet cable that is connected to the pc in trouble.  Any ideas on other things to check.  I made a few adjustments in Win 10 as well.  But no difference.  I can get over 400mbps if I use my iPhone on the WiFi. 

Anybody out there have any other ideas to check on my PC?  Been surfing but can't quite find anything that will fix the issue.

Thanks