U-Verse Connection Issues

We currently have U-Verse phone and home internet service, and within the last two months, my connection has been pretty terrible - constant drops with the service anywhere from 10-30 minutes, definitely feeling like quite the inconvenience at this point.

I've already called the AT&T support number, provided info, and when their basic testing indicates a problem, I've had two technicians visit in the last month- the first of which did some external testing, telling me that due to our rural location, there is no way the current lines can support the speed at which our service was installed at, thus lowering the speed would be in improvement in stability, this seemed to work great for roughly two weeks, right back to square one at this point. The most recent technician ran more tests, indicated that the speed coming in from the line to the house was adequate, but further testing revealed that the signal was far too week inside - I began suspecting the NVG510 was on it's last leg as it was our original unit when the service was installed two years ago - he replaced my gateway from the Motorola NVG 510 to the Motorola NVG 589. After working flawlessly for 2-3 hours the day of replacement, I'm getting even more frequent disconnects and reboots, without even attempting to use the internet. The tech left me his phone number in case of any issues, and after calling yesterday and having him tell me he would call this morning in order to make a stop, we've yet to hear from him - and now the holiday weekend is upon us. I'd rather not allow this to progress a month out.

I've done as much basic gathering as I can, no lines into the house look severed, our gateway is plugged directly into an outlet, (I've tried both power strip, and not) and the only devices we use on the wi-fi are used in a room only 15 feet away from the gateway placement. Aside from our location being fairly rural, and I'm sure the lines aren't the most up to date nor best maintained, (trees everywhere) I have a hard time believing that it's all the sudden causing so many issues after two years of great service... I've read here on the forums as much as I can gather, and tried to disable IPV6, cycled the power to the gateway, (unplugging, replugging - waiting, etc.) and even tried one factory reset, all to no avail, I pulled up my diagnostic logs and see a few lines indicating issues, but honestly this is super confusing to me.

Ideas to check?