Issues with Internet dropping and slowing down frequently

Good morning @user_vvd1p1, and thanks for posting to the Xfinity forums, I hope you are having a good day. As someone that works from home I can understand the importance of a good connection, both with download and upload. You have reached the right team that can take a look into this issue for you. Could you please send our team a direct message with your full name and full address?
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I had a second tech visit scheduled a few days ago.  Initialy, it was the same song and dance from Xfinity that we are seeing everything fine on our end and it could be your line going through the house or your modem.  The tech was more knowledgeable and understanding when I was telling him and showing him the data that the connection works fine at times and drops out from time to time.  We moved the modem to outside Xfinity box and the issue was still present so we ruled out the home line issue.  Luckily for me, the drop in connection happened when the tech was there and the tech was able to record the drop in service it at the utility box.  He said that the problem is upstream and some other team will need to fix it.  

I also showed the low power on upstream channels to the tech and his response was that he has no way to increase upstream power levels.  These power levels do not meet the specifications of my Arris SB8200 modem which is on the Xfinity approved list.  We also discussed putting in splitter in the line to increase upstream power level but that would also decrease downstream SNR/MER which the tech didn't want to do as the line was already on the lower end of the range.  Researching this issue and talking with someone knowledgeable on this, I have learned that installing a Return Path Attenuator will increase upstream power levels.  Discussing this with Xfinity tech, he told me that they don't have this available to them as they only carry Forward Path Attenuators.  This is strange as Xfinity techs should have the tools available to fix upstream power level issue.  

Xfinity sent me a text yesterday that outside maintenance work is completed and I should be running fine now.  The internet has gotten better but the issue is not completely resolved.  The upstream power levels are currently running 34-38 dBmV compared to Arris spec of 45-51 dBmV for my modem.  I am still seeing T3 timeouts recorded in the modem event log.  

The root of the issue is that Xfinity is doing a poor job in maintaining their infrastructure and their first response is to blame the customer's equipment or line.  Maintain your equipment and lines and be proactive in fixing issues as they arise.  Otherwise, you will lose customers as alternatives are now available.