Since 2/17/17 packet loss and slow upload speeds

I'm one of those tech savvy guys who tests his network on a regular basis. I use a 2013 Apple Time capsule as a router and a Netgear CM500 modem, w/ Cox ultimate. My tests between Cox's internal speedtest, speedtest.net, and the Xbox One's network test have consistently been about 230-235 down, 30-35 up. They've always been within less than 5% of each other. Suddenly on 2/17/17, I noticed my downloads were slightly lower(around 200 down) and my uploads were cut in half(15 up). I ran all 3 speed tests(Xbox One-hard wired, speedtest.net, and Cox's internal speedtest). All 3 had the same poor results.The Xbox One showed 1-3% packet loss, which has NEVER happened before(again, I use all 3 speed tests on a regular basis, no previous problems). Pingtest.net has also been showing packet losses of 1-3%. I use that site ALL the time, never had packet load before 2/17/17. Cox tech came out, determined it was the router, because he said hard-wired from the modem to his laptop, things were fine. Tech leaves, I hard wire the modem directly to the Xbox One, 95 down, 3 up, 3% packet loss-no router involved. I hard-wire my Macbook laptop directly to the modem. Uploads are STILL half of what they should be thru speedtest.net and Cox's internal speedtest. Pingtest.net still show 1-3% packet loss. I buy a new modem(TP LINK TC-7620). Cox Rep on phone says IMMEDIATELY showing packet loss, signals all over the place. Hard wired laptop from new modem-no router involved, still showing 1-3% packet loss at pingtest.net, slow uploads(roughly half). Hard wired Xbox One directly to new modem, packet loss is 1-3%, uploads are still 2-3mbps up. All done w/ new ethernet cables from the new modem. There are no splitters between the coax cable from the wall and my modem, except for the connector from where it actually enters the the wall. Cox tech is coming again, between 3-5 pm Phoenix time. Desperate for advice.