Packet Loss/Jitter Issues

For a while I have been having problems with stutters while gaming, particularly at later hours around 7-10PM. The last few months has grown increasingly worse. With this last week making most things unplayable. I have a dual monitor set up and first started looking at PING tests while playing. With stutters in gameplay I would still ping within my plan for 150mbps. I was originally on a router/modem combo and upgraded in hopes it would fix the issues. I ended up getting significant T3 time outs but have since fixed that issue with a replacement device. Now when I conduct packet or jitter tests I am receiving severe losses. Packet loss tests will show anywhere from 10% as high as 47.7% with averages being between 13-20%. Jitter is almost always just below 100ms or slightly above around 120-130ms.

I have a direct line from the outside of the house into my modem. The original line wasn't long enough so there is a connector between the two lines to lengthen the cable but there is no splitters. Before replacing the entire line, I am wondering if anyone might have an idea how to fix this.