Internet is slow

Hi @user_fanta,

Thank you for reaching out and creating a new post. I appreciate you taking the time to use the Xfinity Forums. I understand you have speeds issues which are performing well under the 1 Gigabit speeds you mentioned. Getting down to 20-40 Mbps is certainly low I agree. 

I saw your direct message, but we can troubleshoot here on your post as get started. As a heads up, we ask that you please wait for a request before sending a direct message. This helps us track the incoming post/comments to ensure nothing falls through the cracks. 

When you test speeds, are you testing via hardwired connection? If not, are you running the speed to gateway test or running the test over Wi-Fi on your device? 

I'm located in Western Massachusetts and have a 400 Mbps download Xfinity plan but in late January and for the first two weeks of February, download speeds were consistently less than 100 Mbps and then, during the second week of February were as low as 5 or 6 Mbps (I use ookla for speed tests at https://www.speedtest.net and create a running record of my test results). After restarting and then fully resetting my ARRIS SB8400 modem multiple times, checking all cables, restarting my Dell desktop, etc., without any improvement, I called Xfinity customer support three times to complain.  Each time the customer support person reset my modem, claimed to run diagnostics and then asserted the internet signal coming to me was fine and the problem was on my end, likely with my modem, and I should contact ARRIS support (for $50 a session). So I ordered a new ARRIS SB8400 modem that had the latest firmware v.3.  But, two days later, and after I made no other changes, my internet speeds suddenly returned to 400-500 Mbps speeds which continue. So it's obvious that the problem was with Xfinity and that the mostly offshore customer support folks appear to lack the tools to adequately diagnose problems with Xfinity itself. Have others had similar problems?