Max download speed at my Xfinity modem is less than 100 Mbps - My plan is for up to 600 Mbps.

@EG​ Thanks for your suggestion.  After disconnecting my wifi router from the modem to eliminate it as a potential problem source, I plugged my PC directly into my Xfinity modem via ethernet and then power cycled the modem, the internet speed remains less than 100Mbps at the modem.  My plan is for up to 600Mbps.

Same issue here, for 12 hrs a day my internet connection is less than 100 Mbps down when I pay for 400 mbps, during those times it will drop internet connection constantly 

Hello, @ubermk3. We appreciate you taking the time to reach out to us via Forums. You'll certainly find a lot of helpful discussions and if for any reason none of them work we are always more than happy to step in! @EG is one of our amazing experts that helps our community. ❤️

We'd like to take a closer look and the signal into the home. Please send a Direct Message with your full name and address.

Here are the detailed steps to direct message us:
• Click "Sign In" if necessary
• Click the "Peer to peer chat" icon (upper right corner of this page)
• Click the "New message" (pencil and paper) icon
• Type "Xfinity Support" in the to line and select "Xfinity Support" from the drop-down list
• Type your message in the text area near the bottom of the window
• Press Enter to send your message

Hello @ScruffyMonkey thank you for reaching out and sharing that you are having similar connection issues with speed and the service dropping out. If you have bypassed wireless connections / routers and are hardwired to the modem with a CAT5e or better ethernet cable and not using a VPN the trouble may be RF signal related to a connection issue with the wiring/splitters/amplifiers in or outside your home. I would love to help out and troubleshoot the intermittent/slow internet connection with you. I know it's a vital service and I want everyone to be working with the speed and reliable connection you should have. 

The link that @EG shared (Thanks @EG) Is extremely helpful since it goes over the hardwired connections and offers tips on troubleshooting the signal levels, physical connection/cable issues, security software, etc. It's a lot of information. I would be happy to walk you through the steps as well to help out with the process and get your connections back to where they should be. Send us a direct message with your name and service address. We will help out from there. 

Please send us "Xfinity Support" a direct message with your name and service address.
To send a direct message, please click on the chat icon in the top-right corner of the screen, and select "Xfinity Support" to initiate a live chat. 
Click "Sign In" if necessary
Click the "direct messaging" icon or https://comca.st/3J0ir1l
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

Thanks! I received your message and will be replying shortly @ubermk3!