Constant T3 time-outs & connection drops even after replaced gateway 3x

I am having constant connection drops, over the last several weeks, with constant T3 time-out errors in the gateway logs. I have replaced the modem/router twice (once with an older one that I still had on hand, and then with a brand new gateway Surfboard SBG6782-AC) for a total of 3 different gateways.  The IPs have been reset multiple times, after disconnecting the gateway overnight, and after the equipment changes. I have also had the signal reset 4 or 5 times. 

The connection drops for anywhere from a few seconds, to 10 minutes or so at a time. Usually, it returns on its own, but sometimes, I have to restart the gateway to get it back. It is extremely disruptive to my productivity. When the connection is stable, I have excellent speed according to speedtesting (50+mps) but I do not feel the benefits of this because of the constant timing out. I am seeing the connection drop every few minutes, making it impossible to do anything online. 

I have connected the gateway to a cable outlet in a different room, to make sure that the problem was not with the individual connector. The problem actually seemed worse in the other room. I have no TVs connected to any cable outlets at all, as I am not paying for TV service.  I still got constant T3 time-out errors in the gateway logs.

I have a desktop connected to the gateway by ethernet, a laptop and ipad connected by wifi. I have tested disconnecting each of these devices and using one at a time, to see if I can isolate the problem to a particular device, but there is no change. The connection still drops constantly.

Here is a a screenshot of my gateway connection results  http://screencast.com/t/QjFjT2AMMkq

Here is a screenshot with a sample of my most recent event log. http://screencast.com/t/xcGJah8Z2lk6

Any idea what could be going on here? I have googled this problem until my eyes bleed, but I can't find a solution. Do I need to have a technician out?