COX Gigablast wtih CM1000v2

Thank you for replying but none of the information you provided had any impact on the speed. Internet is still struggling to run at 300mbps consistently. There has to be some other issue other than the modem and/or my devices which is what the tech support rep. decided the problem was when rebooting the modem didn't work. 

No, I do not have the panoramic modem/router.

The Netgear CM1000v2 is approved.  It's not a router.

i'm guessing that providing your own modem is the problem.

I removed the wall plate and the cable line feeds into a plastic box that I cannot remove. Without being able to remove that box, I'm unable to see how exactly the cable is ran. However, you mentioned something that may be on the right track. I notice that my PC says I'm on a network labeled, "network 3." When i spoke with the tech support person, they said everything looked good on "network 1." Does this mean anything? If so, can Cox change the network they send the signal to or does this have to be done manually by a technician?

A plastic box...inside your wall?  Could the box be a electrical PVC box or something else?  It's weird.

Your PC...I'll assume is Windows 10.  Windows 10 creates firewall profiles for "different" networks on the same Ethernet adapter:  Network 1, Network 2, Network 3, etc.  It renames them perhaps because something renegotiated or something.  It's weird too but normal.  As Kevin noted, however, Cox would not be able to observe your network names.

My biggest concern was just any faulty splitter.

A few contributors have reported gigabit speeds.  Their questions were about other things Internet...such as pinging.

I wish cox was not bad sometimes.