Flickering Issue

So our family has had a longstanding issue with our internet service that comes and goes, but in the past month it's the worst it has ever been. Our internet speed is fine, we have gigablast, we use both wifi and hardline connections.

However, we get intermittent service interruptions throughout the day. The connection flickers briefly (2-10 seconds) up to a dozen times each time it happens. It can go days without happening once or it can happen 8+ times throughout day for multiple days in a row. This wouldn't be an issue if all we were doing was watching streaming services, but when work needs done that requires a constant steady connection or when playing video games online, it becomes a nightmare or flat out impossible.

Resetting router/modem doesn't fix it, internal cables and devices work fine, technicians have come out at least a couple times a year to confirm bandwidth is correct, which we have explained to them isn't the problem. When the connection is active, it's great, it's just the random drops that are happening. Every time we try to deal with this we have to start from square one doing the same scripted customer interaction for 3-6 hours on a phone just for a technician to come out and tell us there's no problem. 

As I type this, the connection has flickered at least 8 times in the past 30 minutes. We can't upgrade to fiber either, because it is not yet available at our location and we have no idea when that will change. If that was coming out soon, we would maybe be willing to try that.

This forum post is our last ditch attempt to get this fixed after years of frustration, because more services are now being installed in our neighborhood by other providers and even if the speed ends up being slower (which I don't see happening as I believe those services offer fiber), it can't possibly be worse than dealing with this. Any help is greatly appreciated!