I am not getting anywhere near the 1.2 gb download speed plan on xFi Gateway

@wutang007 

We've seen posts here that show that some Dell computers have a program that limits download speeds (like a type of QoS (Quality of Service) feature). I'm not sure of its name but it may be called Smart-Byte. But if you can find it, disable / remove it and see. YMMV. 

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

Could you post your signal stats and error log from your gateway?  If you're getting 500mb on a 1.2Gb connection using an ethernet cable it'll probably show up in the signal stats and error log if it's a line problem.  A little info on them here:  ‎Internet Troubleshooting Tips | Xfinity Community Forum  It works best to just cut and paste them rather than taking a screen shot.  The forum does quite well with pasted tables and the result is generally more readable than a screen shot.  Please be sure to redact any IP or MAC addresses (CM-MAC, etc.) from the signal stats and error log (particularly the error log).  The forum regards them as private personal information and will block your post if you do not remove them.

Latitude... is this your personal machine or an employer issued machine?  Just asking because Latitudes are common as company issued machines.  Props if it's yours.  I prefer business model laptops for my personal laptop.  At my last job we had eSet antivirus and SentinelOne on all our laptops and they couldn't break 500mbps on a local lan speed test because of all the scanning that security software did.  The local speed test was against OpenSpeedTest running on my Linux box, so it was over http.  Anything http and the security software pegged a couple CPU cores at 100% and throughput maxed out at 500mbps.  My personal laptop gets ~2400mbps using a 2.5Gb USB ethernet adapter on the same test.  eSet and SentinelOne aren't the only things that could do this.  There's lots of obnoxious, performance crippling security software out there.

Could you please send our team a direct message with your full name and full address? Our team can most definitely take a further look at this issue. To send a "Peer to peer" ("Private") message:
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• Click the "New message" (pencil and paper) icon
• Type "Xfinity Support" in the "To:" line and select "Xfinity Support" from the drop-down list which appears. The "Xfinity Support" graphic replaces the "To:" line
• Type your message in the text area near the bottom of the window
• Press Enter to send it

Why does this have to go private at this point ? That kind of defeats the purpose of a public help forum such as this is, no ?... They haven't even returned here yet with an answer to my question... Why not ask some general self-troubleshooting things first which is in keeping with the intent of what these public help forums were designed for so that all readers here may benefit.