Sorry for the long post. This is kind of a two-parter question I guess.

1. My ISP is xfinity at the 200 mbps down speed. Its low but its works fine with me, I’m the only one using it. I am using the ARRIS SB6141 modem that I purchased in 2016. Earlier this year I upgraded my wifi router to the TP-Link AX3000 WiFi 6. A few months after upgrading, I began having internet outages. These last 5-20 minutes usually but can come in groups over an hour or so. Each time they happen I’ll check the xfinity app and it says it can’t see my modem. Often, xfinity will say that maintenance has been done recently in my area, and today during my outages it says that work is due to start tonight at 1am, but not that work is being done currently at the time of the outage. So my first question is wanting to know what is the cause of my outages: Modem, router, or ISP?
2. I obviously can’t rule out Xfinity being the cause, though outages like this have been pretty rare for the past year or so. Its odd that the trouble started around when I got my router, but if that was the culprit then why would the app say its the modem it can’t see? Also, resetting my router doesn’t really seem to do much of anything. Often I can just sit and wait for internet to resume. This leads me to believe that if it isn’t Xfinity and not my router, that my modem might be going. It is pretty old now. So for my second question, if the outages are caused by my modem, I will need a new one. Would upgrading to a DOCSIS 3.1 modem on a 200 mbps down plan bring any noticeable enhancements to my daily life? Futureproofing aside.