My internet speed is getting worse and worse and I've called twice now. What do I do?

I've been having internet issues related to packet loss and ping and latency spikes and fluctuations for over a year now, and the last 5 months have gotten worse and worse. My family pays for 18 mbps down and 1 up, and RARELY get those results. My latency/ping is never constant, its always fluctuating, and the past 2 days now it has gotten worse and worse. We contacted customer service twice now, both times they said that they "fixed the problem", but it never was fixed. Not trying to sound mean or rude, but we've had this problem for a long time, and we still have had no definitive solution. Our router is an nvg510, which is pretty old. My Family and I suspect its the router that is the one causing the problem, and we've requested an upgrade, but it has been denied, for reasons that it doesn't seem wrong. I've tried everything from going into the GUID of the modem and tweaking the WIFI settings like the channels, but that never worked, I've tried factory resetting, and unplugging and plugging back in. I've also tried using a different DNS server for my pc, but that hasn't worked either (I'm on a Ethernet connection btw, the ping issues are STILL there with ethernet, sometimes even worse). I've really been disappointed in the lack of solutions that we have received. Here's a command prompt result from windows 10 that shows a latency test to a website. (its 100 different pings, note how the latency is always fluctuating) 

C:\Users\noahg>ping 8.8.8.8 -n 100

Pinging 8.8.8.8 with 32 bytes of data:
Reply from 8.8.8.8: bytes=32 time=738ms TTL=118
Reply from 8.8.8.8: bytes=32 time=715ms TTL=118
Reply from 8.8.8.8: bytes=32 time=115ms TTL=118
Reply from 8.8.8.8: bytes=32 time=310ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=493ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=273ms TTL=118
Reply from 8.8.8.8: bytes=32 time=297ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=24ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=24ms TTL=118
Reply from 8.8.8.8: bytes=32 time=363ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=21ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=484ms TTL=118
Reply from 8.8.8.8: bytes=32 time=785ms TTL=118
Reply from 8.8.8.8: bytes=32 time=315ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=789ms TTL=118
Reply from 8.8.8.8: bytes=32 time=645ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=817ms TTL=118
Reply from 8.8.8.8: bytes=32 time=710ms TTL=118
Reply from 8.8.8.8: bytes=32 time=35ms TTL=118
Reply from 8.8.8.8: bytes=32 time=713ms TTL=118
Reply from 8.8.8.8: bytes=32 time=715ms TTL=118
Reply from 8.8.8.8: bytes=32 time=75ms TTL=118
Reply from 8.8.8.8: bytes=32 time=635ms TTL=118
Reply from 8.8.8.8: bytes=32 time=790ms TTL=118
Reply from 8.8.8.8: bytes=32 time=136ms TTL=118
Reply from 8.8.8.8: bytes=32 time=472ms TTL=118
Reply from 8.8.8.8: bytes=32 time=785ms TTL=118
Reply from 8.8.8.8: bytes=32 time=327ms TTL=118
Reply from 8.8.8.8: bytes=32 time=107ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=644ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=24ms TTL=118
Reply from 8.8.8.8: bytes=32 time=497ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=285ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=24ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=24ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=453ms TTL=118
Reply from 8.8.8.8: bytes=32 time=292ms TTL=118
Reply from 8.8.8.8: bytes=32 time=808ms TTL=118
Reply from 8.8.8.8: bytes=32 time=536ms TTL=118
Reply from 8.8.8.8: bytes=32 time=121ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=626ms TTL=118
Reply from 8.8.8.8: bytes=32 time=774ms TTL=118
Reply from 8.8.8.8: bytes=32 time=148ms TTL=118
Reply from 8.8.8.8: bytes=32 time=240ms TTL=118
Reply from 8.8.8.8: bytes=32 time=774ms TTL=118
Reply from 8.8.8.8: bytes=32 time=467ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=465ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=806ms TTL=118
Reply from 8.8.8.8: bytes=32 time=98ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=23ms TTL=118
Reply from 8.8.8.8: bytes=32 time=22ms TTL=118
Reply from 8.8.8.8: bytes=32 time=527ms TTL=118
Request timed out.
Reply from 8.8.8.8: bytes=32 time=24ms TTL=118

Ping statistics for 8.8.8.8:
Packets: Sent = 100, Received = 89, Lost = 11 (11% loss),
Approximate round trip times in milli-seconds:
Minimum = 21ms, Maximum = 817ms, Average = 249ms

I usually, when its not fluctuating, get around 22 ping, and now, even late at night its always fluctuating. So I ask this, what can I do that I have not already done? Please help

P.S The reason why I think it's the router is due to the ethernet activity light. It says that the blinking light goes in sync with the data transfers, well its just blinking non stop with no pauses or anything like that. Its just very fast blinks. Before, it would usually have breaks in the blinking where its just a solid light, but now its just constantly blinking