Inconsistent Internet Speed and Up and Down Service

For the past two months my service (1.2Gbit service using the xfinity router (white)) has been experiencing the following:

1. Slow speeds. I have run speed tests consistently, using the xfinity app and my own browser. the reported speeds range from 20Mbit to 300Mbit, with an estimated average of 80Mbit. It spends considerably more time at the lower end during the day when the least number of connected devices are active. 

2. Inconsistent Up-Time. My wife and I work from home. Video conferencing without fail, drops multiple times every day due to dropped connections to xfinity. We have to use our verizon hotspots to reconnect and keep going. I reboot the router a couple times a day, both hard reboots and I use the xfinity App to restart the modem.

I have inventoried the number of devices (42) currently connected in my network. Not all use internet but they are all connected to my network.

Vivint home security

4 iphones

3 TVs

8 Amazon Alexas

4 PCs (1 used for gaming; 3 laptops for work)

15 smart plugs

2 smart light bulbs

2 nest thermostats

1 Traeger grill

1 HP Printer

1 wifi extender for the basement

1 Sound bar

I also have xFinity TV for which there are two boxes.

I have called on a few occasions and they sent a tech 1 time. The tech checked all the coax connections which were solid. he then said it is something outside my home. I asked if he would report that so it could be checked and repaired. He said yes (8 weeks ago)...

I have used the app to also check the xfinity signal coming from the outside to my xfinity modem/router. It tells the story (which I am doubting) that there is 1.2-1.4 Gb coming into my house. but I run a speed test and it registers 30Mb. How is that possible?  It seems to point to the router being bad, or the wifi service being overloaded. 

I am looking for a fix to get my network working as it should.